On October 31, 2009, it's a quiet Halloween night at Margaret's Diner (one corner of the almost-illustrious JJ's Fuel, Tool, and Stool Truck Stop).  There are a few customers, but the main rush is over.  Other than a few jack o' lantern stickers on the window, it's a night just like any other.

Any other, that is, until a withered old man walks into the diner with a twisted pushcart carrying a heavily decorated espresso machine.  He is wrinkled, one of his eyes rolls lazily, and he grins to show teeth yellowed with age.  He invites everyone to have a taste of his holiday spirit and gives each a paper cup with black, black coffee.  Some try to put creamer and sugar into the drink, but it refuses to lighten at all.  Still, it's free coffee, and they drink deeply.

They are:

Joel Cannon, 35, trucker (played by Preston)
Bobby "Hammer" McHammer, 17, busboy (played by John)
Carl Lebitz, 35-ish, short-order cook (played by Paul)
Stephen "Mac" MacDouglas, 24, trucker (played by Joe)
Margaret, 47, cashier (played by Janica)
and the great "Majestico", a traveling magician (played by Chad)

With them are Martha & Jim Hatterson, a young couple on their honeymoon after a Justice of the Peace marriage
Gretchen (63), one of Margaret's waitresses
and Cooter Johnson and Shorty Oakes, two local farmers in convenient red plaid shirts.

They mill about for a moment, getting their bearings, with a few still feeling woozy and others inducing vomiting just in case this was a bad trip.  Finally they notice a billboard behind the green city sign, reading, "Just got into town?  Come by the Halloweentowne Visitor's Center for information, maps, and free doughnuts!  777 Poe Avenue."

They decide to head into town, but a scream rings out from the forest, and "The Cannon" decides to go see if anyone needs help.  Majestico and others follow, but not so quickly.  As they go into the forest, they notice the floor becomes hard and flat.  Carl checks the earth, finding it to be flagstones.  Clearing leaves, they discover them to be flat covers of old graves.  Twisted trees have grown up among them, throwing some akimbo.  Meanwhile, the Cannon goes deep into the forest until he finds a pretty young woman in Germanic princess dress swooning in the low branches of a half-fallen tree.  He tries to pick her up, but he notices her dress is caught on something.  Trying to free it, he realizes the dress isn't caught at all:  her legs are roots growing into the fallen tree.  Her eyes open, revealing not irises, but wooden bark.  He lets out a shout, and the party scatters, some to help, others to get into the clearing on the highway.  Jim & Martha run into the woods on the other side of the road and are never seen again.

The wooden princess grabs hold of Cannon, and he struggles to get free.  Majestico goes in deeper after him.  He sees that the trees are moving, the bark cracking and releasing dried mummies moving stiffly like wooden puppets.  He lets loose a blast of stage-fire from his sleeves, which aid in the situation, but he and Cannon are very much outnumbered.  The rest of the party runs, turning back only to fight the mummies who pour out of the woods.  Finally Cannon and Majestico break free, and everyone flees down the highway until they can no longer run.

Finally, headlights appear, heading toward them.  They step to the shoulder of the road, trying to waive down the car.  The headlights jerk suddenly toward them, and the car proves itself to be the haunted Deathmobile, driverless and bloodthirsty.  Most of the party is able to dodge out of the way, but Gretchen and Majestico are stuck.  Gretchen comes out bruised and dazed with a few cracked ribs, but Majestico is unable to walk.  Deathmobile screams down the highway, pursued by two police cruisers.  One cruiser continues the pursuit while the other pulls off and investigates.  A young policeman hops out, checks on everyone, and radios for an ambulance.  He mutters a few things about how insane the night has been.  Margaret tells him he reminds her of her fourth husband.

Down the road, the sky lights up with a thunderous explosion.  After a moment of stillness, the Deathmobile swings through again.  The cop dives behind his car while everyone tries to get out of the way, but the Deathmobile smacks the car, sending it spinning.  The cop is crushed, and the Deathmobile drives off into the night with a sputtering muffler that sounds vaguely like laughter.

The party waits until the ambulance finally arrives.  The crew seem exhausted, but not yet overwhelmed.  They pack up the injured Gretchen and Majestico with one of the farmers going along.  Everyone else piles into the police car, swiping some guns from the trunk.  They put the address of the visitor's center into the GPS and drive into town.  The city is quiet but for Halloween parties and various trick-or-treaters.  Passing a housing edition, they see a house surrounded by barbed wire fence and shut-off floodlights with a sign out front reading, "For Sale."

After following the mostly quiet streets and seeing more emergency vehicles pass, they finally come to a turn-of-the-century brick three-story building labeled "Halloweentowne Visitor's Center."  The lights are on, but thick steel shutters are drawn over all the windows.  The party goes up and knocks on a heavy steel door.

There's a pause, and finally the door opens to reveal a scrawny young man in glasses peeking out.  He asks in a trembling voice, "Did you just get into town?"

They reply that they did.  He stumbles inside and nearly faints.  They come inside to find a sort of community center with an office, open room with a ping-pong table, a kitchenette with sandwiches and chips, and a door leading to a back room.  A bronze plaque on the back wall says it is funded by the generous donation of "The Gregory Weiss Foundation."

When the guy finishes mumbling about him being "only an intern" and "it is true", he directs them to the back room where a few folding chairs and a TV are set up.  The guy, named "Mark" apparently, pops in a tape.  A man with a scraggly graying hair and wearing a faded flannel comes on the screen.  He explains that he is Greg Weiss and that he, too, is from the real world, trapped in this nightmare that happens every Halloween.

"If you're watching this, then it means I'm gone," the man says.  "With any luck, it means my monster is destroyed.  More likely, I'm dead."  He tells them the rules of Halloweentowne, that they are put here to fight a monster pitted against them as some kind of test for humanity, or maybe as some cruel cosmic joke.  He'd been preparing for years and now that he was gone, he passed along all his possessions to this foundation to hold them for people trapped in the years to come.  He'd hidden caches of weapons all over town, in addition to stashes of potentially evil magical items in the basement.

The movie ends, and the party understands that they must kill their monster.  Mark weeps, not wanting his reality to be true.  They sit him down and make him record himself saying all these things are true, marking it to be played next year to remind him (as the natives seem to forget every year).  After going into the basement and coming out with interesting-looking, potentially magical items out of lead boxes, they decide to go to the nearest cache marked on one of Greg's maps: at the top of Hallows Tower.

Meanwhile, the ambulance with the others hurries toward Halloweentowne General Hospital.  One of the paramedics complains of a bite one of his patients gave him earlier (strange green tooth-marks).  Just before they arrive at the hospital, the driver stops, saying there's some kind of riot going on.  As they look more closely, they notice it is a horde of zombies storming the emergency, not a riot at all.  As some of the zombies turn toward them, they drive away.

Suddenly the bite-marks on the paramedic fester and burst, spewing out green goo.  The goo explodes and consumes the ambulance, causing the driver to crash.  The paramedic, driver, and the farmer are consumed.  Majestico's spine miraculously reattached in the crash, and he was able to help the second paramedic get Gretchen to safety.

As they hunker in the street, watching the swirling goo consume the ambulance, the rest of the party meets them.  They take Gretchen back to the community center to wait with Mac and Cooter (the remaining farmer) while the others go after the cache.  They pull up to the tower, check the map again, and see the handwritten notation that it's on the roof.  Margaret distracts the lobby guard (telling him he reminds her of her eighth husband) while the others take the elevator and stairs toward the roof.  They pass an office party on the seventh floor, a guy in the devil costume riding partway up the elevator with them.

On the roof, they search until they find a weather station marked with the Weiss Foundation plaque.  Inside, there's an arsenal of semi-automatics and explosives, along with holy water, bags full of various spices, and charms of all kinds.  They load up until they hear a wafting sound of sea shanties on the wind.  A ghostly pirate ship floats out of the sky and begins to "board" the tower.

The party throw shots and explosives behind them, but those only slow the pirates.  They run as fast as they can, barely escaping past the office party, which is swallowed up by the pirate raiding party.  The party try to fight a few off, but Majestico becomes wounded by friendly fire.  They eventually retreat to the police car and speed back to the Welcome Center.

There, they leave Gretchen and Cooter, then go with Mark to make certain his family is safe and perhaps find another weapons cache.  As they drive through town, more and more monsters are appearing.  They see a gang of vampire gangsters from the late '20s sitting outside of the city blood bank crying and flipping coins.  On the corner leading to Mark's house, they see a shadowy organ grinder and give him a large leeway.  At the house, Mark's parents are fine, and they tell them to load up with weapons and first aid, then to get to the Welcome Center and lock it down for safety.  Margaret tosses Mark a butcher's knife to carry, and he cuts himself trying to catch it.  They notice that the blood quickly becomes swallowed by moss.  Looking at Majestico's wounds, they notice similar moss covering any of the blood exposed to air.  With a sixth sense, they know this is their monster.  Clearing the moss only exposes more blood, and they only manage to seal the wounds by pouring a strange silver fluid they found in the basement

With Mark's family on their way, they decide that they need help to figure out how to cure invisible spores in the air.  Cannon volunteers that he knows where he can get some help.  They drive back to the blood bank and slowly approach the vampire gangsters.  The blood bank is dark and empty with flecks of moss growing around its open door.  They yell, "Hey, Vlad!"

The leader of the gangsters (coincidentally named Vladdigoli) looks up at them.  They parley, and the vampires admit that all the blood's been turned to moss.  Any blood that reaches air all over town is automatically infected.  They're stuck without victims.  The party tells them that their only hope is to help.

Vlad agrees.  After asking about places plant research might be going on, he tells them of the city Arboretum.  They decide to go, Cannon volunteering to ride in the vampires' gangster car (where he tempts them with his neck, much to their chagrin).  Vlad sends two of the vampires, Fangs and Louie, off to gather the clans as they might need more help.

As they drive, they come to a street swarming with rats like a river.  They drive carefully over them and decide not to investigate what they're running from, or to.

They reach the Arboretum, seeing a peaceful grove of trees.  As they come to a bridge, the vampires stop, confessing they cannot travel over the running water.  They wait, and the party goes ahead to investigate the research center deep in the dark woods.

They pull into the parking lot where they find two trucks and a Prius.  The welcome center in the middle is quiet, and they can't see well into the offices, but the greenhouse on the opposite end is lit.  Majestico and Margaret go to spy on the greenhouse, finding white-coated lab techs working feverishly over vials and Bunsen burners.  Using fertilizer and a few spare gas tanks, the party rigs up makeshift flamethrowers.  Cannon, meanwhile, begins to hear unseen whisperers in the bushes.  They dig too deep, and a gremlin pops out of the tool box of one of the trucks, attacking Mac.  The fight is manic, and the gremlin dives into Mac's shirt, clawing at his chest and belly.  The others eventually rip it out, and the gremlin flees into the darkness.

The lab techs look up at the noise, and one of them, a shaggy-haired surfer guy, goes to investigate.  Majestico and Margaret hurry around to warn the others.  They lay a trap at the door, and when the tech pops out, they tackle him and beat him up, the Cannon sitting on his chest.  They tell him they know about the moss, and he seems surprised.  Finally, the guy convinces them to trust him, and he brings them into the greenhouse.  They meet the head of the Arboretum, Dr. Holihauser, who discovered the moss and is working to understand it.  Margaret says he reminds her of her thirteenth husband.  He confesses their work has been of little use as they have such scant research material.  They tell him that the city blood bank was all turned to moss, ample samples.

Dr. Holihauser yells, "To the Prius!"

After the Cannon deals with the whispering voices by setting fire to the Arboretum (he hears the screams of the trees), they lead the scientists back to the bridge, picking up the vampires, and they all return to the blood bank.  The vampires leave them, going to find the last remaining clans who haven't heard their beckon.  The scientists go inside while the party stands guard.  Cannon and Mac head down the street to a liquor store in search of materials for Molotov cocktails (and something to sip).  They notice the store is empty and the cashier has drunk himself to death behind the register.  As they come out, they stumble upon an enormous anaconda slithering through the streets.  Filled with liquid courage, Cannon decides to take it on.  The gunfire brings the rest of the party over, and they gun down the massive beast.

Upon their return to the blood bank, they discover it quiet again.  Moss has grown to cover everything and almost seems to move on its own.  Creeping inside, they call for the scientists, but hear nothing.  Finally, in the vault with the empty blood bags, they find the lab assistants covered in moss, twitching and unmoving.

They pick up the least attacked (the surfer guy) and drag him free.  In the front room, he opens his eyes.  They ask where the doctor is.

"He's trying to hurt us," the man says in a groaning voice.  He drowns as the moss grows thicker.

Deciding that it was the doctor that attacked him, the party leaves the blood bank.  Throwing the Molotov cocktails they'd made into the building, they burn it to the ground.  The moss seems to scream as the fire burns.

As the blood bank burns, a horde of vampires marches up the street.  They have vampires of all kinds: the gangsters met earlier, a few clad in cowls and Austrian jewels, sinister Blade-style techno vampires, whiny emo vampires in too much makeup, burly half-bats, a band of hillbillies, Nosferatu, near-mosquitoes, and on and on.  Vlad approaches the party along with one of the Counts and an Asian vampire whose head floats just above his body.  The party explains the doctor has run and disappeared.

The vampires scatter, finally collecting the fleeing doctor.  They drag him bound in spider-silk back to the party.  He screams and begs not to be killed, explaining that he didn't attack his lab techs, he merely fled after the moss overwhelmed them.  He explains that it is continually growing stronger and more and more blood is consumed.  It has gained a telepathic sentience among the moss spores everywhere, even control over bodies.  He tried to flee back to his lab with materials, then skip town to flee to a remote area and somehow decipher a cure.

The party demands a cure immediately.  He says he isn't capable of such a thing, but he might know someone who is.

Driving their half-broken police car and moss-specked Prius before a parade of vampires, the party comes to the looming tower home of Dr. de Muto.  The doctor answers the door, sees the army of vampires, and closes it again.  The party bang on the door until he opens it again.  They try to explain the situation but fail until Dr. Holihauser uses sufficiently nerdy language.  Dr. de Muto agrees to help, but he does not invite any of them inside.  A rumble of grumbling rings from the crowd of vampires.

The party and Dr. Holihauser go up to his attic laboratory without his overt permission.  It is a room filled with archaic machines, Jacob's ladders, and a steel bed on chains leading up to a skylight for thunderstorms.  Margaret says it reminds her of her twenty-second husband.  They begin research using moss spores in the air, mutating dust mites in hopes that the machine will eventually spit out a fast-spreading species that will consume the moss.

Meanwhile, the moss become conscious of the danger against it, so it rallies its growth for an attack.  A sort of snowstorm begins, followed by marching bodies of moss flowing from every direction.  Mind-controlled humans and animals are mixed with the pure moss, swarming over the laboratory.  The vampires let out a bloodthirsty (literally) battle-cry and counterattack.  From above, the party unloads their guns repeatedly and throws explosively.  The battle goes on epically.  All the while, the doctors and Margaret quietly test mite after mite spewed from a radioactive machine.

A moss-covered giant eagle swoops from the skies and begins to tear holes in the roof.  Carl climbs up and attacks it, beating its head in with a Latin-covered cane.  The bird lets out a death-rattle and falls to the ground below.  Gradually, the moss stitches its head back together, and the injured giant bird begins to claw its way back up the tower.  Meanwhile, moss-infected squirrels and even an orangutan break into the lab, and the party must gun them down to protect the research.

Below, the vampires are becoming overwhelmed.  While they have no blood to infect, the weaker ones are eventually pinned under the sheer growing mass of the moss.  The stronger vampires fight on, but without blood to refresh them, their injuries add up.  The moss, meanwhile, continually grows its own repairs, and its army marches to the very threshold of the house.

Just as all seems lost, Dr. de Muto lets out an impressed, "Humph!"  He takes a vial with seemingly nothing in it, goes to one of the broken windows (the party killing mossy monsters all around him), and upturns it, giving the vial a pat on the bottom to sprinkle something out.

An ear-piercing shriek sounds from all directions.  Unseen, a growing species of mite bites into the moss.  It tries to flee, but the mites grow innumerable with so much moss to be eaten.  Within a matter of minutes, the vampires begin to turn back the tide of battle, and the moss begins to disappear.

The party swoons, and they find themselves back in the diner in the late hours of the night.  Gretchen is with them, covered in blood and shivering; Cooter nowhere in sight.  But, life goes on for them.  Mac never quite overcomes his fears and spends the rest of his life in and out of mental hospitals.  The Cannon returns to his life as a trucker, but he develops a phobia of fire and the dying screams of the Arboretum ring constantly in his ears.  Bobby decides that, after surviving such a night, nothing can ever scare him again, and he becomes an obscenely wealthy high-stakes businessman.  Carl makes up for his past deeds and, using funding from Bobby as tax-write-offs, builds a very successful Second Chance camp for wayward teens.  Margaret, meanwhile, meets her twenty-third husband, and this one sticks:  together, they turn her diner into a moderately successful chain around the Midwest.  Majestico, meanwhile, continues his career well, and sometimes his tricks go off even better than he anticipated, almost as if he brought back a little actual magic from that Halloween night...