Recap: Star Trek Deep Space Nine S 03 E 20 Improbable Cause
After a bomb destroys Garak's shop, Odo thinks Garak knows more than he's telling. When his initial prime suspect, a Flaxian assassin, is killed by the Romulans, Odo goes to secret connections in Cardassia for information.He learns that five other ex-operatives of the Obsidian Order were killed on the same day. Garak recognizes the victims as fellow associates of Enabran Tain, former head of the Obsidian Order, so he and Odo go looking for Tain.
They find Tain on a Romulan ship, where he has come out of retirement and joined up with peers in the Tal Shiar, the Romulan secret service. They have assembled a secret fleet of Tal Shiar and Obsidian Order ships withwhich they plan to attack and destroy the Founders' home world in the Gamma Quadrant. Tain admits that he gave the orders to kill Garak and the five others, to eliminate those from his past who knew enough about him to get in the way. Since Garak survived, Tain gives him a chance to join him again, which Garak accepts.