The episode opens in an airport; a man arrives and heads to Customs, where he's identified as Gary Lester. He says he's visiting a friend and traveling alone. the Homeland Security agent seems suspicious and shortly, he's sitting in an interrogation room with a strange bottle on the table in front of him. He's being interrogated by a different officer, who thinks that the bottle is related to injection marks on Gary's arm. He takes it, then drops it and hundreds of beetles pour out, flying to the ceiling, then descending into the guard's mouth.
Constantine and Zed are spending some time at a local park, where she's happy. they talk about drugs, and about psychic energy. He tells her that she just needs to know her boundaries, then she can know what she can really do. She starts to see a vision -- coins falling from the sky -- but time is frozen and Manny arrives, asking John if Zed will be able to make it in their team. Constantine tells him that they only need her to deal with the rising darkness. Manny says he's worried John will scare her away.
Constantine asks him why he's there, and Manny says he's not, then disappears and time resumes.
Constantine and Zed head to the mill house, where Constantine says he wants to work on Zed's training. It appears the house has been broken into, and he tells her that she might want to stay outside -- that the intruder is almost certainly trapped inside by Jasper's magic. They enter and a number of beetles are in the mill house; lights are flickering. Gary is there, floating in midair. John recognizes him immediately.
John hasn't seen Gary (Gaz) since Newcastle, when Gaz vanished. He isn't impressed with the drug use either. Gaz said he just needed to escape after everything with Astra. Zed asks who Astra is, and Constantine ignores the question, asking Gaz what he's got himself into.
Gaz says that it's bad, but that he didn't mean for it to happen. It started out as a bender, and he got lost. The next thing he knew, he was in the Sudan and recognized a man with containment markings all over his face. He knew somebody had trapped a demon in the man, and took his chance to atone for what happened in Newcastle. He couldn't resist; he had to. HE exorcized the demon from the man, which left him in the form of a swarm of beetles that he trapped in an old bottle, closing it up.
Constantine and Zed want to know where the demon went -- Gaz just looks at them, but then the camera cuts to the officer who had been interrogating them; he's storming around the airport, stuffing his face with any food he passes and roughing up anyone who objects.
It culminates with him bare-handing some food out of a deep-fryer and then dropping dead, the beetles pouring out of his mouth.
Back in the mill house, Constantine is carving a Seal of Solomon -- like a Star of David with a circle around it -- into a bottle using "the ring of Solomon," a finger-mounted device that was sent from Heaven to trap genies.
He tells Zed that Gary is hopeless; that he burned through is family's money with some help from John and the Newcastle crew. He won't tell Zed what happened at Newcastle. He says that Gary's is a life wasted, and now John is going to find the demon, which possesses a woman coming out of the bathroom. She charges through a supermarket on a similar mission to eat everything in sight -- including the cheek of a security guard who tries to stop her.
Constantine guilts Gaz about having loosed the demon on the world, and likens the Hunger Demon's mindless consumption to Gaz's addiction. Zed tries to convince John otherwise, but he woni't bring Gaz with him.
Gaz explains to Zed after Constantine leaves that everyone in their group looked up to John and went to Newcastle mostly to be around him; he tells her what happened to Astra, that John had been trying to get a demon out of her when he damned both of them by mistake.
He gets light-headed, but when Zed goes to catch him, she has a vision of his taking hard drugs.
At the supermarket, Constantine fakes his way in and then gets a woman and her son to tell him what they saw: the swarm, upon leaving the body of the woman who died, entered the body of a meat delivery driver.
Based on the logo the kid describes, Constantine tracks the driver to a cooling facility, where he finds the driver already dead and a butcher gorging herself on a carcass on the floor. John tries to get the demon out of her, and she charges at him, backwards and on all fours. he traps the demon in his bottle briefly but drops it, and has to trap the swarm in a freezer.
Back at the mill house, he comes and asks Gaz how he managed to capture the demon in the first place; he realizes quickly that something is wrong with Zed, and tells the pair that the Hunger Demon is unusually strong. He's trapped it for now but it will escape soon.
Zed has sketches of the man Gaz exorcised. Constantine feels the markings on the man's face tells them what they need to know, and goes to see a shaman.
At an African grocer, he finds Nomo and tells him about the Hunger Demon. He says it's from the Sudan, but he's not sure if that's where it originated. He shows Nomo the sketches, and Nomo names the demon, but says he doesn't know how to stop it. He says they can travel together to discover answers, but it's a psychadelic called The Mist that will do the "driving."
The pair take it and start to hallucinate wildly; in the trip, they trade eyes (it's surprisingly graphic for network TV), and Nomo starts telling John the history of the demon; it was originally trapped by a shaman who sacrificed a boy to the demon, marking him to trap it and save the rest of the community. The demon was supposed to consume the host and thus itself, but instead was saved by Lester.
In order to stop the demon, John needs a mystical blade like the one the shaman used.
At the mill house, Lester tells Zed that he feels trapped and useless, that he is convinced he could beat the Hunger Demon again. Zed tries to stop him, but he touches her, subjecting her to all his pain and addiction, and then running while she's incapacitated by the psychic weight of it.
At the meat locker, the freezer is off its hinges and everyone in the building is dead.
Constantine returns to the mill house, where he finds Zed crashed out on the couch. He asks her what happened and she won't tell him, so he explodes at Gary (not present). She tells him Gaz is going after the demon. Constantine doesn't believe it, saying that between thought and action, there's always temptation for addicts.
He finds a pair of drug dealers beating Gary, and rescues him by offering them a dose of The Mist. At a bar, he tells Gaz that he saved him becuase he's a friend, and Gaz says tha the's not a real friend, that he betrayed John and Astra. He says that he was high at Newcastle and couldn't focus during the seance -- and that he panicked and hid when things went bad.
Constantine told him that it wasn't Gaz's fault -- that he shouldn't have involved the others, especially Gaz. He says he doesn't blame Gaz, that he had every right to be afraid. He tells him that everybody has the capacity to change. He tells him that they're going to go catch the demon together.
Constantine heads to a museum, where he's going to create a diversion so that Gaz can break in and steal the knife they need. Before he can bust through the doors, though, Manny stops time, asking whether John is sure he wants to trust Gaz and go after the demon. John says he can do it, and Manny leaves, restarting time. As a security guard stops John, Gaz heads in to steal the Kusa knife, picking a lock to do so.
Cut to John, who has apparently hypnotized the guard, who is now dancing. He's convinced the guard that the alarm is music, and he won't stop dancing until it stops going off. Gaz brings the Kusa, and John praises him, then they leave to head to a theatre where they saw a news report that suggested the Hunger Demon was.
Inside, somebody is gorging himself on popcorn; Constantine says they need to get started. They head up onto the stage, and Constantine tells Gaz that one of them has to be a sacrifice. He offers to draw straws, but Gaz realizes that John's plan all along was to sacrifice him. He's at first upset, but Gaz says that it's his chance ot make his life mean something, and that there's no better way to go out than as a mae like John Constantine. John tells him that he's proud of him, kisses his forehead and they start. Gaz kneels, and John gets behidn him, presenting him to the demon with an incantation. The swarm leaves the person on the theatre floor and heads into Gaz, who continues to nod in readiness. Constantine carves the binding spell into his friend's face, and Gaz passes out in his lap.
Zed is furious that John is sacrificing Gaz, and that John manipulated him into doing it. He says he warned her that people around him die -- and that she should go if she can't handle it -- but she decides to help get Gaz into a secure room where he can die with John holding his hand and Manny looking on.