As another convoy of Jem'Hadar ships emerges through the wormhole toward Cardassia, Sisko and his officers face the grim realization that the Dominion is taking over the Alpha Quadrant. When Starfleet Command notifies Sisko that he must stop further Dominion reinforcements from reaching Cardassia, he decides to mine the entrance to the wormhole -- a move that may cost them Deep Space Nine and will likely lead to war.