The episode opens in the woods, where a couple are huffing paint. They stare up at the moon, talking about whether or not they should be spending their life getting high, when a large lizard-like monster attacks a nearby man and then scares them.
They rush to the aid of the man who had been attacked, who says he’s fine, but then they see a body on the ground with damage to his neck.
At the X-files office, Mulder is upset that many of the old x-files have been explained by science and the Internet. He’s disillusioned by the fact that his life seems to be basically a joke. Scully comes in and tell them they’ve got a new case, and it has a monster.
In the woods, Mulder and Scully talk about the case; the surviving victim was an animal control officer. Mulder argues the victim — and three more found in a lair nearby — were likely killed by a wolf or a mountain lion.
Scully says it doesn’t matter whether Mulder is bummed out or not, that finding whatever’s killing people will justify itself.
Not long after, cut to the monster from earlier attacking a prostitute at a truck stop. She stops it with a blow to the head from her purse.
At the truck stop later, Mulder and Scully are talking with the prostitute, who says the creature had horns and was wearing underwear.
After a brief chat with the animal control officer, who’s there investigating a call about a loose puppy, Mulder and Scully hear a roar and go to pursue it. While Mulder is trying to get a photo of whatever is out there, they happen on another body.
Not long after that, both Mulder and the animal control officer are attacked by the monster, and Mulder gets a photo. They see it run past again and see somebody enter a Port-A-Potty, but when they open the door to take a photo, it’s just a man in a hat. Whey they leave him alone, he steps back out of the toilet, and the horns on the back of his head disappear.
At the morgue, Mulder is showing blurry photos and selfie video to Scully. He tells her that he believes the creature shot blood at him out of its eye, and that he thinks they’re looking for a man-sized horned lizard with human teeth.
At the motel later, Mulder is awakened by screams. It’s the man at the front desk, cleaning himself up and drinking rubbing alcohol.
Heading back to a trashed room, Mulder finds a bag from a cell phone place empty, the mirror on the wall broken and a a hole in the wall where a mounted animal head had been, leading to a corridor.
There are such holes in the wall for every room in the place.
Back at the main office, Mulder comes out th other end of the corridor to find the man still drinking his rubbing alcohol. When the man questions him coming out of the corridor, Mulder shows his FBI badge. He tells the man to come clean about what he saw in the trashed room, and the manager tells him about a man having a seeming psychotic episode, and then morphing into a were-lizard. Mulder shows him the photo of the man on the Port-A-Potty and the sketch of the monster that the FBI made based on the paint-huffing witness accounts. The manager confirms it’s the same in both cases.
At Scully’s room, Mulder is pitching a variety of monster theories to Scully, and providing her rebuttals for him. Eventually he wraps up, saying he doesn’t know what it is, just that it’s a monster. Mulder shows Scully photos to suggest the were-monster was wearing stolen clothes from a victim, and said he took some medications that could help lead them to the suspect.
At a psychiatrist’s office, Mulder hears a story of a were-lizard, which the man reduces to psychology. He says he was reminded of the myth because the patient to whom he prescribed the anti-psychotic had similar delusions.
He tells Mulder that he suggested to the man to take a walk in the cemetery next time he feels an episode coming on, and offers that he thinks Mulder is crazy for believing the story.
At the cell phone store, Scully calls Mulder and says she’s found their suspect working there. She tells him that the blood tests from the lab had some discrepancies, but he has already hung up before she can explain.
At the cell phone store, Scully tells the man she wants to ask him some questions. When Mulder arrives, the place is trashed. Scully tells him that the man threw a fit and ran to leave.
Mulder runs out, heading to the cemetery. He places flowers on a grave, and stands next to the man, who’s been drinking. Mulder tells the man to get whatever’s bothering him off his chest, and the man says he wants to kill Mulder, then smashes a green bottle of gin and goes after Mulder. He wants Mulder to take the bottle from him and use the green glass of it to stab him in the appendix — which is how the legend says the were-lizard has to be killed. Mulder says he will kill him, but first he wants to hear the man’s story.
Flashback to that first night; in lizard-mode, the man is relaxing when a pair of men are fighting. The monster tries to scare one of the men off, but one man attacked him, biting the monster. The man describes the man who attacked him as a predator and says that his lizard-mode is when he’s “normal.” He says the next morning, he awoke and found himself suddenly in human form. He had his first human thought, and realized he was naked. He claims that’s when he stole clothes from nearby dead bodies, and that once clothed he became possessed and felt compelled to get a job.
Mulder has a hard time believing the man’s story — even he says he doesn’t understand half of what he’s saying. He tells a story of getting fast food and watching porn at the hotel — until during the night he changed back into his normal state. In the morning, though, he became human again — much to his dismay.
Whenever he got to work, he felt compelled to trash the place and quit, but he was too overcome with fear to do so. He tells Mulder that when he visited the psychiatrist, the medication didn’t help. He got himself a puppy, which made him happy, but the dog got away when housekeeping came the next day.
As a human, the monster says, he realized how pointless life is. He says he saw the man who bit him. He was about to attack the man, until he saw the man kill somebody else. Transforming, he shed his clothes and hoped to go out into the wilderness again, but was struck by the prostitute and had a concussion. He can’t remember most of the rest of the night. This morning, he got up, went to work and then when Scully came in, the two had sex.
Mulder tells him to stop, that this part of the story didn’t happen, and the man stands by his story briefly, then claims he has to lie about his sex life.
Ultimately, Mulder is upset that he can’t believe the man’s fantastical story, while the man is upset that Mulder was just looking to take advantage of him to get him to confess to murders he didn’t commit. The man leaves, and Mulder drinks a second bottle of gin that had been stashed away, waking up later to a phone call from Scully.
Scully is at the animal control office, where the animal control officer from earlier not only hasn’t quit, but attacks her. Mulder calls for backup and directions, then finds his way to the animal control shelter; when he gets there, Scully has already taken down the animal control officer. She takes a dog out of a cage on the counter — he’s actually the one Guy (the monster’s chosen name) claims to have adopted earlier.
That night in the woods, Mulder tracks down guy to tell him they found the killer. The man’s taking his clothes off and heading into the woods for hibernation.
Mulder questions whether the man’s kind hibernates, since he looks like a lizard, but the man says that’s racist. He claims their hibernation cycle is 10,000 years and that he hopes this is all over by the time he wakes up. Mulder says that’s impossible, and when Guy is upset that he doesn’t believe him, Mulder tells him “I want to believe.” That makes Guy say he’s glad to have met Mulder, and reach his hand out to shake. By the time the handshake is over, he’s in his lizard form and runs off into the woods, leaving Mulder thrilled to have found something to believe in.