Mulder has to battle John Barrett once more, a convicted criminal who he helped to put away but who now seems to have found the perfect disguise, youth.

The episode starts when we see in a flashback to 1989, John Barrett being operated on supposedly dead except we see him blink. Years into the future, Mulder and Scully go to investigate a jewellery store robbery, nothing for the FBI to get involved in except Reggie Purdue, Mulder's old friend has requested that Mulder looks into it. Mulder realizes that Barnett is back looking for revenge when he reads the message left at the crime scene, "Fox can't guard the chicken coop". This is Barnett's calling card.

Scully, obviously skeptical, looks into Barnett's records and finds he did die in prison four years earlier but even this doesn't put Mulder off. Instead he goes to Agent Henderson , fingerprint specialist who tells Mulder that it is 95% Barnett which convinces him further that he is truly alive.
Later Mulder finds another note from Barnett saying "A hunted Fox eventually dies' and when an anonymous caller rings up Mulder threatening him but sounds exactly like Barnett, Mulder is totally convinced and rings up Purdue to report the new evidence. Except, Purdue is strangled on the phone by Barnett and another note is left at the crime scene, "Funeral first for Fox's friends - then for Fox".

Upon further investigation the agents find that Barnett's prison doctor who pronounced him dead, Dr. Ridley was experimenting on inmates trying to reverse the aging process.When he shows up at Scully's house, he tells them that Barnett was Ridley's ONLY success and that Barnett looks younger than he really is.

Mulder meets with his infamous informant, Deep Throat who tells him that the American Government are currently bargaining with Barnett for the research that Ridley found out. Meanwhile, Scully finds her answering machine is being traced and she finds Barnett's fingerprints all over it. Barnett now knows that Scully is meeting a friend at a cello recital so Mulder and some other FBI agents stakeout the meeting hall where Barnett manages to shoot Scully and run off taking a hostage. Mulder shoots Barnett having not done so years earlier which cost the life of a FBI agent.

Scully is fine but Barnett seems destined for the grave as the agents watch government officials struggling to keep Barnett alive. He dies. Mulder reflects that he fears the agents haven't heard the last of John Barnett.