112. In Purgatory's Shadow

Summary

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 Bashir, who has been replaced on DS9 by a Changeling. Tain dies, acknowledging that Garak is his son. Meanwhile, Kira discovers a massing Dominion fleet, meaning that invasion is finally imminent. Sisko makes the decision to close the wormhole. But the station's emitter array has been sabotaged, and our heroes watch helplessly as the first wave comes through.

Summary provided by The DS9 Encyclopedia and Lexicon by kind permission of Tracy Hemenover.