The team meets in the new regional office for Verdant Technologies in Chicago. 5 strangers shuffle nervously around a desk as their tired boss, Mr. Samson, looks over his notes. The room is incomplete with a wall missing and bare drywall showing on the others.
After a moment, Samson addresses them. He has them introduce themselves each in term: Alyssa Ortega, previous team member and security expert; Dorian, part of a company drug testing program; James Reynolds, a transfer from management; Mason Olsen, an accounting manager and new team leader; and Richard Brian, corporate researcher in search of field experience.
Their cheerless boss briefs them on their mission. People have gone missing in Lewisburg, PA. Over 10 people have disappeared in the town this summer. The local authorities have turn up nothing. Lewisburg hosts Bucknell University and 3500 students are due to arrive in a couple weeks.
Their mission is to Lewisburg and search the town for the source of the disappearances. The company wants them to keep careful track of their own experiences and any anomalies they detect in their perceptions. If they encounter any extranormal entities, they are to capture them and radio for recovery.
The retrieval team makes some requests before leaving, getting supplies of tranquilizers and restraints. Olsen calls ahead to the Lewisburg authorities and talks to the local sheriff, Barbara Cox. He explains to her that they are investigating the disappearance of a company employee and asks for her help. She offers to give them a tour when they arrive.
The drive to Pennsylvania is long and boring, passing through endless stretches of farmland and pockets of forest. Driving into the night, some people try to catch some sleep in the white company van. Suddenly Alyssa swerves to avoid hitting something. Alyssa asks what it was but noone seems willing to discuss it. They pass a sign welcoming them to Lewisburg.
They pull into a ratty motel. Olsen confirms their reservations with the night manager, a cheerful man named Tim Dyer. Dorian’s eyes grow as he notices that the veins in Tim’s bright green eyes are not red. They are green.
No one else notices however and they arrange themselves in their rooms. Alyssa takes the farthest room next to Reynolds. Olsen and Brian share a room to defray costs, taking the room with a door into Dorian’s to keep an eye on the disturbed artist.
While Reynolds enjoys a good night’s rest, Dorian tosses and turns, plagued by visions of the manager’s green stained eye and the sound of rushing vines. Alyssa wakes up in the night to find the TV talking to her. She shuts it up by pushing it over, breaking the ancient machine. This causes Dorian to go out and see what happened. The two talk but neither is willing to discuss the strange stuff they’ve seen. Both however keep careful notes about what they experienced.
Later that night, Olsen and Brian hear someone talking outside their window, playing at something like marbles and making bets with strange items: milkteeth and last gasps. They jot down everything they hear.
As down breaks they are awaken by a bird chirping out a song like a car alarm. Olsen and Brian investigate outside their room while Alyssa takes a jog. The two men find a loose circle in the dirt that stains the parking lot. Someone was out here last night. Alyssa meanwhile tours the small town. The sleepy village is quiet with only a large black dog trotting around. The wolfhound carefully watches her from across the street. Finally Dorian gets up and has his pills. He notices that he isn’t having his usual cravings.
The team enjoys a continental breakfast. As they eat they open up about their various experiences. Brian reveals his research into last night’s “visitors”. The terms used point to the existence of a fairy market. Dorian also notices that the morning supervisor, Mrs. Dyer has her husband’s green eyes. Weirdly when asked, she explains it is because they are married.
As they chew on that mad tidbit, they notice some children hurrying down the street, apparently fleeing a large black dog. The team quickly finishes their meal and follow the kids down to the road. As they reach the edge of town they find the fields overgrown with vines. The eventually notices them and runs off into the brier patch.
As they talk to the frightened children, the sheriff pulls up. while some them try to extract information from the children, Olsen keeps the officer occupied. He convinces her to call animal control while they take the children back home themselves. The children claim that the dog was really a wolf. One of them tells the team that kids have been going missing and mentions Tommy as one of the victims. The sheriff explains that Tommy’s folks moved away. The team however notes that the sheriff has green eyes.
While Alyssa and Reynolds take the kids home, the rest of the team goes to the Sheriff’s Office. Olsen uses his contacts to put some pressure on the sheriff’s secretary. They find that she (and the drunk in the cell in the back) are both normal. Olsen is able to convince her to give him the records of all the disappearances that summer. The team finds that most of the victims are from the poorer areas of town.
Brain meanwhile talks to the drunk, a jaundiced individual who thinks the town is being taken over by aliens. He says he has seen lights in the woods behind the university. He thinks that people are being replaced and mentions that the water tastes funny. The drunk manages to convince the scientist to give him some beer money.
Meanwhile Alyssa manages bring one child home. The second however seems to resist. She confides that they have the strange green eyes afflicting half of the town. The monster hunters decide to take both remaining children to the final parent.
They find April Lockwood at home. The normal seeming woman works at the university and with a little encouragement agrees to take care of both kids. Alyssa leaves a business card with her after asking if she had any strange experiences. Drinking some bottled water, the young woman says no but that she will keep it in mind.
New information in hand, the team regroups behind the university. Entering the woods, they find them suspiciously overgrown with dense nests of thorn bushes. The plants seem to be almost visibly growing around them. Following a trail they find their way to a pump site for the local water works. One of the pipes has sprung a leak and a pool of water surrounds it. From a careful examination it looks like someone has attempted to fix the leak.
Dorian meanwhile is distracted by a beetle that lands on his hand. Looking closely he sees it has a human face. He flicks it off, sending it screaming and relays his discovery to the others. Brain takes samples of the water while the others notice the sunlight dimming from approaching clouds.
Then a chipmunk starts talking to them. From it they learn that the animals around here are getting smarter and stranger. They are looking forward to the market which will arrive once the storm breaks. As it talks it references something called “over there” which is where these vines and the “Big Bad Wolf” came from. It also reveals that people with green eyes have been infiltrated by “over there”.
Thanking the chipmunk, they decide on their next move. The pipes lead to the university and the chemical plant. Deciding that the plant might be putting something in the water they drive north.
Rain begins to fall, growing quickly in force and speed. The team heads to Walmart to gear up. Alyssa gets a rifle while Brain works on a makeshift flamethrower. They also get some machetes. Then they try to leave town. The fields to either side of the road turning into blurry overgrown fields of brambles. The vines seem to be growing towards the road, closing off the town.
Suddenly they find themselves turned around, heading back to town. Realizing something strange is going on they stop. From the van they can see vines visibly growing along the side of the road as the storm rages overhead. They also notice a chemical company truck by side of the road a few hundred yards away. They drive up and get out to investigate.
They find the portly occupant looking over his GPS, trying to find his way out of town. While Olsen talks to him, Brain investigates in the back and finds a tank filled with BSNX-8. They confront the employee of Edron and he reveals the truth. The man, Scott Norris, was ordered to put a special mix of chemicals into the water and test the concentration hourly. But then he noticed people acting weird, seeing things. Then the kids started vanishing. He’s sure they are putting something like LSD into the water. He just wants out.
They let him go and he heads for the bridge, hoping to escape town that way. Then they get a call from April. The woman frantically tells them that vines are growing all around the house and that the university professors are cutting up people. The team drives to house as fast as they can.
They pull up onto the lawn. As they hack the door open, Alyssa tries the flamethrower. The device fails and the leave the soldering tubing there, taking April and the two children with them.
As they reach the university, they find the vines consuming it. Using the excess flame thrower fuel they create a ring of fire and use themselves as bait. Soon a monstrous wolf and a towering witch climb out of the darkness.
Alyssa snipes wolf twice before it tears into Reynolds. The team gangs up on the monster, shooting and beating on it until it collapses. In that time the witch has manages to cross the flames, shrouding itself in fire and grabbing Alyssa from the top of the van. The team’s bullets ring off of its armored apron. But while Alyssa slices into it with her implanted metallic claws, Dorian crashes the van into it killing it.
The team grabs the bodies and escapes the rapidly disappearing town. Late they learn that the very existence of the town has disappeared from existing records.