A coded message comes through the wormhole from the Gamma Quadrant, which Garak recognizes as a signal from his old superior and mentor, Enabran Tain, who had been presumed dead in the Dominion massacre of the Obsidian Order/Tal Shiar fleet. Worf and Garak are sent to investigate, but they are captured by Jem'Hadar and put in a prison where they find Tain, the real General Martok...and someone familiar from DS9 who has been replaced by a Changeling. Meanwhile, Sisko is faced with an imminent Dominion invasion, and must make the decision to close the wormhole.
