O'Brien comes to believe that his friends are plotting against him.
O'Brien returns from a meeting about security for peace talks with the Paradas and finds Keiko, Molly and the senior staff acting oddly, keeping secrets and watching his movements. Even Odo appears to join in, and when his crewmates try to sedate him O'Brien flees the station in a runabout, telling the story in his log as he heads for the Parada system.
On the planet he learns the truth: he is not the real O'Brien but a Paradan-made replicant who believes he is the Chief, built to kill the rebel leaders at the peace talks, while the real O'Brien was held captive. The replicant is shot, and as he dies he asks the real O'Brien to tell Keiko he loves her.