In
Pittsburgh, Leonard Betts (
Paul McCrane), a paramedic, is decapitated when his ambulance collides with a truck. Later, at the morgue, his headless body leaves its cold chamber, knocks out the attendant, steals his clothes, and escapes.
Fox Mulder (
David Duchovny) and
Dana Scully (
Gillian Anderson) visit the morgue, where they find Betts's head in a
medical waste dumpster. Scully attempts a cranial examination, but the head's eyes and mouth both suddenly open when she begins the procedure. Meanwhile, Mulder goes to Betts's apartment, where he finds the attendant's discarded clothes. When Mulder leaves, Betts—who has regrown his head—rises out of his iodine-filled bathtub. Mulder interviews Michelle Wilkes (Jennifer Clement), Betts's former partner, who recollects his ability to detect cancer. When an interior slice of Betts's
polymerized head is examined, the agents discover his
frontal lobe displayed signs of pervasive cancer. Mulder has
Chuck Burks (
Bill Dow) subject the slice to a
Kirlian photography test; the final image shows a
corona discharge that takes the appearance of human shoulders. Using fingerprint records, Scully learns that Betts shared fingerprints with a man called Albert Tanner. The agents visit his elderly mother, Elaine (Marjorie Lovett), who informs them Albert died in a car accident six years previously. Meanwhile, Wilkes tracks down Betts at another hospital and confronts him. After an apology, he gives her a lethal injection of
potassium chloride; Betts is then pursued and captured by a security guard. After he is handcuffed to his car, Betts escapes by tearing off his thumb. The agents search the car the next morning, finding disposed tumors in a cooler in the trunk. Mulder believes Betts subsists on the tumors, and that his nature makes him the embodiment of a radical leap in evolution. Upon learning the car is registered to Elaine, the agents have the police search her home. Elaine recounts how her son endured bullying as a child "because he was different", and says "he had his reasons" if he killed anybody. Meanwhile, Betts accosts a bar patron and kills him to obtain his cancerous lung. Later, in a storage unit, he seems to shed his body and create a duplicate. When the agents come across the storage unit, the duplicate Betts attempts to flee in a car, which explodes when fired upon and seemingly kills him. Scully suggests Betts's first death as Albert Tanner was staged, but when they exhume Tanner's casket, they find his body still inside. Mulder becomes convinced Betts can not only regenerate his body parts, but his entire body itself. Because of this, he believes Betts is still at large. At Elaine's behest, Betts removes a cancerous tumor from her body before summoning an ambulance. The agents, already staking out Elaine's house, encounter the paramedics when they arrive. Scully accompanies Elaine to the hospital while Mulder conducts a search of the neighborhood. However, after arriving at the hospital, Scully realizes Betts has stowed himself away on the roof of the ambulance. Betts locks her inside the ambulance with him, calmly but apologetically telling her, like his earlier victim, she has "something I need". After a struggle, Scully kills Betts by pressing charged defibrillator paddles against his head. Scully remains silently stunned by Betts's suggestion she has cancer. Later, in her apartment, she wakes up with a cough and nosebleed, confirming her illness. ==Production==