When Starfleet tightens security measures on Earth and institutes martial law to combat the Changeling threat, Sisko and Odo begin to investigate a suspicious trail of events that imply all may not be what it seems.

Stripped of his former rank, Dukat returns to escort Major Kira to an intelligence sharing conference between Cardassia and Bajor. However, when a Klingon Bird-of-Prey attacks the conference, Kira and Dukat unite to hunt down those responsible.