Mulder and Scully travel to a sleeply town in Mississippi where a tornado has affected a man who has the power to walk through walls.

At a prison farm in Mississippi, inmates are nailing plywood over windows because of a wind storm. One inmate, Pinker Rawls, assaults another, and is put "in the box," as punishment. The box is a small shack in the middle of the prison yard. A tornado passes through and the shack is blown three miles away. Rawls is thought to be dead. The Captain of the prison farm is found in his office, his body cut in two.

Scully examines the Captain in the local morgue. It is as if a narrow section of the middle of his body was burned through. Scully speculates about spontaneous human combustion, but Mulder is convinced it was murder. In the Captain's office, he finds a section of the exterior wall is so brittle that he can easily knock holes in it. That night, a police officer finds Rawls in a clothing store and arrests him, handcuffing him, but as the officer makes a radio call, Rawls escapes and drives off in the police car. Visiting the scene, Mulder discovers that the handcuffs are now so brittle that he can easily snap them in two.

Rawls goes to his former residence, where he had lived with his girlfriend, June. He knows the man who lives there now, who also lived with June after Rawls was sent to prison, but she moved out four years earlier. The man shoots Rawls several times, but he is not injured. When Mulder and Scully arrive, having traced Rawls' last known address, they find the man dead, the inside of his skull burned out. Eight years ago Rawls robbed a "wire office" of $90,000 and it was never recovered. He is apparently looking for the money. Mulder thinks Rawls can pass through solid objects, changing their composition - possibly caused by the tornado. They can find no trace of his ex-girlfriend, June, but they locate an address for her sister, Jackie.

Rawls gets to Jackie's first, walking through a wall to question Jackie, but Mulder and Scully drive up and Rawls leaves. Jackie and her son are not hurt. Burned into a wall they find the words "I want what's mine." Jackie tells them where to find June, and they drive off, not knowing that Rawls is in the trunk of the agents' rented car. June tells them she found the money after Rawls was in prison and spent it - on her nice house, a computer, etc. She just wanted another chance. Her current boyfriend is shocked and declines to go into protective custody with her. Putting June's suitcase into the trunk of the car, Mulder finds the metal to be brittle and realizes Rawls is in the area. They don't find him but inside the house they have just left they find "I want what's mine" burned into the wall, but the burn stops at a mirror. Mulder theorizes that if his power is based on elecreicity, then non-conductive materials could be used to stop him. He orders rubber riot bullets. Scully finds medical paperwork from seven years earlier indicating that June had a child.

Rawls follows June to a safe house and kidnaps her, killing the officer guarding her. On a lonely side road, in a stolen station wagon, June confesses that she had a son, Trevor Andrew. Meanwhile, Scully determines that there is no adoption record. They realize that Jackie's son might really be June's. Rawls and June show up at Jackie's. Rawls meets Trevor and scares him by locking June in a storage closet. Jackie throws hot soup at Rawls, but it passes through him. Trevor runs outside and Rawls follows. Trevor runs to Mulder and Scully, who have just arrived. As Scully takes Trevor back to the car, Mulder fires rubber bullets at Rawls, who ducks through a wall and escapes. Rawls intercepts Scully as she and Trevor reach the car. They escape him by ducking into a glass telephone booth. Rawls starts to break in, but backs off when he realizes he is terrifying Trevor. June, somehow escaping from the locked closet, runs Rawls down with the station wagon. He passes through parts of it, but the glass windshield hits him and kills him. Mulder finally shows up and June tells him she had to stop Rawls. "What did he want?" she asks. "Maybe another chance," answers Mulder.