Major Kira believes a Valerian ship docked at the station is smuggling weapons to the Cardassians, but Commander Sisko refuses to detain the vessel without evidence. Before they can resolve their conflict, a damaged Klingon vessel arrives through the Wormhole and one of its crew transports aboard Deep Space Nine as the ship explodes. The bloodied man, later identified as the ship's first officer, whispers, "Victory!" and dies within seconds. As the vessel was only supposed to be conducting a biological survey, the crew investigates. While inquiring at Quark's, Constable Odo's head splits in two and he collapses. Quark rushes to find the doctor.

Odo awakens in the Infirmary. Being ignorant of Odo's physiology, Dr. Bashir is unable to find anything wrong with him, but hints at potential trouble between Kira and Sisko. When pressed for more information, he vaguely says it is "too early to commit oneself either way." By now, Kira has found evidence of foul play among the Valerians, and informs Sisko of her intention to confiscate their cargo: he forbids her from doing so. Meanwhile, Lt. Dax and Chief O'Brien take a runabout to find the Klingons' mission recorder.

During their trip, O'Brien mentions the mounting tension and makes his loyalty to Sisko clear to a complacent Dax. They find the mission recorder and bring it back to the station, where Kira attempts to win Dax's loyalty. While others quickly form alliances, however, Dax appears lethargic and only interested in reminiscing about the past. Kira sees Quark attempting to eavesdrop, and violently attacks him.

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