Kira is shocked and saddened when Latha Mabrin, a fellow member of the Shakaar Resistance Cell-turned Vedek, is murdered.
Kira's shock turns to fear, however, when she receives a recorded message moments after learning of the murder. Her message consists of a picture of Latha appearing on the computer screen, and a scrambled voice saying simply, "That's one." Odo is unable to trace the message, which Kira interprets as a threat to all the former members of the Shakaar Resistance Cell. Kira makes arrangements to transport resistance member Fala onto a runabout returning to the station. But something goes wrong during the transport, and Fala is killed.
After what's left of the dead woman's body is removed, an investigation of the transporter reveals that Fala was killed by a tiny detonator programmed to scramble the transporter beam. A message from the scrambled voice saying "That's two" is soon delivered on a PADD. Later, while working on the case in Odo's office, Kira receives a "That's three" message displaying the face of Mobara, another member of the Shakaar. Immediately, they begin efforts to contact him, hoping to stop his murder. Kira returns to her room in O'Brien's quarters to rest, but is jolted by a loud crash outside her door.
Phaser drawn, Kira creeps into the living room, ready to face the assassin. Instead, she comes face to face with Furel and Lupaza, two more members of the Shakaar who have come to help her. Thinking her bodyguard was the killer, they attacked him — causing the noise Kira heard. Furel and Lupaza volunteer to hunt down the assassin for Kira. She prefers to handle her problem within the boundaries of the law, but allows Furel and Lupaza to stay with her in the O'Brien quarters to "protect" her and the O'Briens' unborn child. Later, the grim, but not unexpected, news of Mobara's death arrives. During a staff meeting, Odo surmises that whoever is doing the killing most likely has a vendetta against Kira — and that she is also a likely target. Nog, Dax and Kira work with the scrambled voice, hoping it will provide a clue, but the voice used in the messages turns out to belong to Kira. Their work is interrupted by news that there has been an explosion in the O'Brien quarters. O'Brien was not home at the time, but Furel and Lupaza are dead.
Odo tells Kira that he has compiled a list of possible suspects with the skills, opportunity and motive for these attacks. He refuses to give Kira the list, afraid the very pregnant woman will head off in search of the killer on her own. Kira pretends to have no intention to leave the station, but the moment Odo leaves, she transports into his office, steals the file and shuts down Odo's computer so she can't be followed. Then she takes off in a runabout. After eliminating several suspects, she arrives at the home of Silaran Prin. Almost instantly, she is placed in a restraining field and told she will die.
Silaran, who was severely disfigured in a Resistance bombing, is punishing those involved — especially Kira, who was the ringleader. The bombing in which he was injured, killed civilians, women and children. Silaran himself was not a member of the Cardassian military but was a simple laundry worker, cleaning soldiers' uniforms. He points out that he has not killed indiscriminately like Kira. She counters that the Cardassians were a hostile alien race occupying Bajor, and even if he only provided the military minor logistical support, he was indirectly aiding the occupation, and thus his views are hypocritical. Silaran tells Kira that he will spare her baby, but kill her, and prepares to operate. Kira warns him that this will kill the baby, which is not Bajoran, but human, meaning it has special needs. Silaran is unmoved. Thinking quickly, Kira begs for a sedative, realizing that the herbs she has taken for her pregnancy have rendered most sedatives ineffective. She pretends to fall asleep, then lunges at Silaran, attacking and killing him. Sisko, Bashir and Odo arrive to rescue her, but Silaran is already dead, and Kira, shaken and sobered by her experience, only wants to go home.