The station is full of Klingons who have arrived to help Starfleet fight the Dominion. They are led by General Martok, who is not being open with Captain Sisko about the Klingons' plans and motives. Sisko calls on the one officer in Starfleet who has perhaps the most experience in dealing with Klingons: Worf.
Worf mingles amongst the Klingons on the station and eventually extracts some information. Despite having to inform on his own people to follow orders, he delivers the information to Sisko. The Klingons are planning to attack Cardassia. They believe that the Cardassian government has been infiltrated by the Dominion. They have no proof of this and Sisko tries to convince General Martok it is a bad idea. Martok rejects his pleas and leads the Klingon fleet toward Cardassia.
When Garak notifies Dukat of the impending attack on his world, the Cardassians are able to scrape together a defense. The Federation condemns the attack on Cardassia, and the Klingons promptly withdraw from the Khitomer Accords, the peace treaty between the Federation and the Klingon Empire. Chancellor Gowron, leader of the Klingon Empire, gives Worf a choice: he may join the Klingons, or be a dishonorable traitor to his people.