At the cabin, Shelley eats and lounges. He can feel the worms moving inside him and entering his brain.

In the morning, Newt and Max find Ephraim covered in blood. Newt bandages Ephraim’s wounds. Ephraim begs the other boys to cut the worms out of him. Instead, Newt suggests Ephraim could come back to the cabin and eat some of the laxative mushrooms he gathered for Kent. Ephraim agrees. Newt and Max don’t actually believe Ephraim is sick, but offer him some mushrooms to get him to stop cutting himself or asking them to cut him.

When the boys return, they can’t find Kent or Shelley. Max wonders how he and Newt have stayed relatively level-headed compared to the rest. He concludes that children are better equipped to deal with intense, undying fear than adults are, because they still believe in impossible things whereas adults lack the flexibility to even accept what’s happening in unreal situations.

Erikson still says he and Dr. Edgerton were trying to create a diet pill. However, the interviewer says Dr. Edgerton was receiving two different grants. One was from a pharmaceutical company to develop the diet pill, but another was a three-million-dollar grant from the military to develop a biological weapon. Erikson claims to be shocked by this information.

Newt and Max go to the beach, and Shelley approaches Ephraim once he’s alone. Ephraim asks Shelley to get the worms out. Shelley cuts Ephraim’s ear, claiming to still see worms inside him. He pretends like he can’t quite catch them, though. He tells Ephraim to wait there, and a few minutes later Shelley returns with some gasoline that he took from the cabin’s generator. Shelley convinces Ephraim to pour the gasoline on his body, then burn himself to get the worms out. 

Max and Newt return to camp to find Ephraim on fire and flailing around. Max tries to douse the flames, but it’s too late, and Ephraim dies. Max immediately suspects Shelley is behind the death. Shelley then emerges, and Max confronts him. However, Newt warns Max to stay away from Shelley, who they can tell is now sick. Max attacks Shelley, but Shelley stabs him. Newt then knocks Shelley down with a branch.

Shelley threatens to kill the boys, but struggles to stand up. Max throws rocks at Shelley when he tries to come after them. Eventually, Shelley runs off into the woods. They bury Ephraim and say a prayer.

That night, Shelley wanders around eating. He now views the worms as his babies, who he must protect from Newt and Max by killing the boys. Shelley knows the parasites will eat him alive, but he views this process as giving birth and changing form rather than being sick and dying. There is a voice inside Shelley who argues that the worms are his enemies, but this voice isn’t as loud as the ones advocating for the worms. Shelley plans on being the world’s best father. 

Brewer is an admiral from the Canadian Navy who claims he enacted standard protocol by quarantining the island, meaning nothing (not even inanimate objects) would be allowed in or out of the area. Brewer therefore left the children there knowingly, because otherwise he would risk spreading the illness to many others on the mainland. He also had troops shoot any birds flying off the island. After the incident, they treated the island with chemicals to supposedly eradicate any remaining life forms there.

Newt and Max try to start Tom Padgett’s stolen boat again. Newt gets frustrated and cries. Newt wonders why the man would have removed his own spark plugs—probably he ate them. Max remembers he did see something shiny in the man’s stomach when Tim cut him open.

The boys go to the cabin and layer a bunch of gloves and clothing onto Max’s arm. Max then reaches into the man and retrieves the spark plugs.