In mid-March 1964, Cory Mackenson accompanies his father, Tom, on his early morning milk delivery route for Green Meadows Dairy. As they drive along a wooded road near Saxon’s Lake, a car suddenly emerges from a dirt path and plunges into the water.

Tom dives in to rescue the driver. Inside the sinking car, he discovers the body of a naked man who has been brutally beaten and strangled with a piano wire. The victim is handcuffed to the steering wheel and has a tattoo of a winged skull on his shoulder. As the car sinks, it almost pulls Tom under, but he manages to escape and swim to shore. While watching from the road, Cory sees a figure in a long dark coat standing in the woods across the road, but when he blinks, the figure is gone.

Tom goes inside a nearby house to use the phone while Cory waits in the truck. The house is a brothel run by one of Tom’s customers, Grace Stafford, who comes out to the truck to speak with Cory. Sheriff J.T. Amory arrives and begins his investigation, though the lake is too deep to recover the car. After Cory walks across the road to search the area where the figure had been standing, he returns to the milk truck and finds a small green feather on the sole of his shoe.

Cory keeps the green feather, storing it in a cigar box in his room. A week passes, and Sheriff Amory comes in person to the Mackenson house for a sit-down conversation with Tom, Rebecca, and Cory. He reports that his investigation is stalled: He has searched the lake with rowboats and nets, finding nothing; there are no reports of anyone missing from the area. With no body, he has no victim and no formal case.

The incident deeply affects Cory’s father, Tom, who begins to suffer from repeated nightmares in which the dead man’s corpse pulls him down into the dark water of the lake. He confides in his wife, Rebecca, that he cannot shake the gruesome image from his mind. His greatest fear is that the killer must be a local, someone they know and trust, which shatters his sense of safety in their small town.

In early April, Cory and his friends Ben Sears and Johnny Wilson watch a double feature at the Lyric theater. The second film, Invaders from Mars, terrifies them with its story of parents being replaced by cold, emotionless alien duplicates. That evening, Cory has a sleepover at Ben’s house.

From Ben’s yard, they see a fiery object fall from the sky in the woods west of town. Ben’s father, Sim Sears, ignores his family’s pleas and goes with a man named Donny Blaylock to find where it landed. A weeping Ben tells his father he will “come back changed” (48), making Cory think of the characters in the film. Sim returns home late that night, heavily intoxicated. He has transformed from a jovial man into a verbally abusive drunk, grabbing his wife and raising the flask as if to strike her before Ben clings to his leg and begs him to stop him. Cory witnesses the scene, realizing that the real-world horror of a loved one becoming a monstrous stranger is far more frightening than anything in a movie.

On Good Friday, Cory watches the annual procession of the Black residents of Bruton. Led by their 106-year-old matriarch, the Lady, and the Moon Man, they perform a ritual on the gargoyle bridge, throwing raw meat into the Tecumseh River to feed the legendary local monster, Old Moses.

On Easter Sunday, the Mackenson family attends church. During the service, Cory is annoyed by his classmate Brenda “The Demon” Sutley and pelted with peas by the town bullies, brothers Gotha and Gordo Branlin. The muggy, closed-up church becomes a scene of chaos when a swarm of wasps emerges from a hole in the ceiling and attacks the congregation. In the panicked stampede to escape, Cory sees his Granddaddy Jaybird abandon his family to save himself. Jaybird later returns to press mud against Cory’s stings, but Cory refuses to acknowledge him, filled with a deep sense of shame for his grandfather’s cowardice.

During a week of relentless rain, Cory’s old, rusted bicycle breaks apart and is hauled away by the town junkman, Emmett Sculley, before Cory and his father can retrieve it. As they drive to the junkyard on Route Sixteen, Cory is terrified when he sees what appears to be Midnight Mona, the ghost of a black dragster, speeding up behind them before vanishing. The car belonged to a local boy named Little Stevie Cauley, who died when it crashed and burned on that same road.

At the junkyard, Mr. Sculley tells them the bike has already been fed into a metal crusher. To pacify the upset Cory, he then shows them a large, serrated fang embedded in a piece of river wood, which he claims is a tooth from Old Moses. He has tried to tell the authorities about the creature, he says, but they are uninterested in his stories. As they are leaving, Tom and Cory see the real, burned-out wreck of Midnight Mona lying in the scrapyard.

A dam bursts north of Zephyr, causing the Tecumseh River to flood the town. At an emergency town meeting, the eccentric, perpetually naked Vernon Thaxter appears. The townspeople have long grown used to the sight of the wealthy young man strolling around without any clothes. He delivers a message (or so he claims) from his wealthy, powerful, and mysterious father, Moorwood Thaxter, which effectively blackmails the white townspeople into helping the residents of the predominantly Black community of Bruton save their homes.

While working at the flooded riverbank, Cory sees a tall man in a raincoat and a fedora with a green feather in its band. The man draws something metallic with a sharp edge from his pocket. Before he can investigate, Cory slips and falls in the water, and his mother pulls him back. Later, he and his mother are called away to help Nila Castile rescue her father, Mr. Booker Thornberry, who is having a heart attack in their rapidly flooding home. The adults carry Mr. Brooker out in a wheelbarrow. While waiting for their mothers to return, Cory and Nila’s young son Gavin are trapped in the house by Old Moses. The ancient creature—which resembles an alligator—eats a dog and then attacks them. Cory jams a broom down the monster’s throat, causing it to vomit violently and retreat.

Cory’s friends refuse to believe his story about fighting Old Moses. A few weeks later, the town handyman, Mr. Marcus Lightfoot, arrives at the Mackenson house with a letter summoning Cory and his mother to the home of the Lady. Tom, fearful of the Lady’s reputation for practicing voodoo, refuses to go.

At the Lady’s house, she thanks Cory for saving the life of Gavin, a boy she considers her great-grandson. As a reward, she promises to fulfil his request for a new bicycle. She promises to provide him with a special bicycle through unspecified means involving Mr. Lightfoot, telling him it “won’t come from a store” (130). After Cory leaves the room, the Lady tells Rebecca that she has been having vivid dreams about the murdered man in Saxon’s Lake. She gives Rebecca a drawing of the winged-skull tattoo and explains that the dead man’s spirit is in great pain and is trying to communicate. She warns that if Tom does not come to see her to discuss the matter, the lingering trauma of what he witnessed could destroy him.