15. By Inferno's Light

The Dominion fleet passes through the wormhole and flies off toward Cardassia. The Cardassian officer Gul Dukat joins them, announcing that the Dominion has accepted Cardassia as a member, with Dukat as its new leader.

At the Dominion internment camp where DS9 officers Worf and Dr. Bashir, the Cardassian former spy Garak, and the Klingon general Martok are being held, the inmates have built an illicit transmitter inside the prison walls. Garak crawls inside the walls to modify it to signal their runabout so they can escape, triggering his severe claustrophobia. Meanwhile, Worf is selected as an opponent for Jem'Hadar guards to practice hand-to-hand combat. Worf's refusal to surrender, defeating a series of Jem'Hadar opponents, inspires Garak to overcome his fears and continue working.

Dukat vows with the help of the Dominion that within five days he will remove and kill all Klingons and Maquis from within Cardassian space and also to destroy all who stand in the way of Cardassia becoming a major power in the Alpha Quadrant. As Klingon ships hastily retreat from their invasion of Cardassian space, Deep Space Nine's Captain Sisko persuades Klingon chancellor Gowron to reinstate the alliance between the Klingons and the Federation in order to fight the Dominion. Dukat contacts Sisko, warning that he intends to conquer Deep Space Nine for the Dominion. Sisko deploys the starship Defiant and three runabouts to fight the incoming Cardassian/Dominion fleet; they are joined by the Klingons and a Romulan fleet. Unknown to Sisko, a Changeling impersonating Bashir is at the helm of one of the runabouts.

Back at the internment camp, the Jem'Hadar come close to discovering Garak before being overpowered by the other prisoners. Meanwhile, Worf is fighting Ikat'ika, the Jem'Hadar commander. Worf refuses to yield; Ikat'ika, impressed by Worf's determination, yields the fight. The Vorta overseer, disgusted, orders Worf's and Ikat'ika's immediate execution. As the troops turn their phasers toward Worf, Garak manages to activate the transmitter, and the prisoners are beamed away to the runabout at the last second. There, Bashir sends an urgent message to DS9.

The Changeling Bashir's runabout is carrying a bomb intended to detonate inside the Bajoran sun, causing a supernova that will incinerate DS9, Bajor, and the combined Starfleet, Klingon, and Romulan forces. Receiving Bashir's message, Sisko orders that runabout destroyed. The Defiant takes the risky maneuver of engaging warp drive within the planetary system in order to pull the runabout away from the star where it explodes safely. No Cardassian/Dominion fleet arrives.

Garak, Worf, Bashir, and Martok return to the station and Sisko finalizes the peace treaty with Gowron. Martok is appointed to command the new permanent Klingon presence on DS9.