A Bajoran woman hires Quark to retrieve a strongbox from her former husband's shop on Deep Space Nine. Quark opens it to find a list of Bajorans. A stranger sneaks up, shoots Quark and steals the list. As Dr. Bashir tries reviving Quark, Odo becomes suspicious of Rom. Commander Sisko coaxes him to divulge what was in the strongbox. All Rom knows is that the box was hidden behind a wall panel in the shop during the Cardassian Occupation.
In a flashback, Odo enters a chemist's shop and Gul Dukat shows him a dead body, soliciting Odo to become an investigator for the Cardassians. Although Odo detests the occupation, Dukat claims his superiors wish to "solve" the murder by executing ten random Bajorans. As Odo is neither Bajoran nor Cardassian, Dukat believes him to be an ideal investigator and convinces the shapeshifter to help. The only witness is Vaatrick Pallra, the deceased's widow - the same woman who has hired Quark to retrieve the strongbox. Odo notes that she has not cried. She claims her husband had been having an affair and was murdered by his mistress. When asked to identify the mistress, she points at Kira.
In the present, Odo notes that he never closed the Vaatrick murder case. He resumes interrogating Rom and tries to jog the Ferengi's memory; all Rom can remember is that the first name started with "Ches'so." Kira asks if Odo has found anything. He tells her about the name. Referring to the events of five years ago, Kira says she would have been executed but for Odo's intervention, because the Cardassians did not care about innocence or guilt.
In another flashback, Kira explains to Odo that Vaatrick obtained a type of tea not available to most Bajorans, which he shared with her, but there was no intimate relationship between them. She also accuses Odo of being a "collaborator."
In the present, Odo asks Pallra why her husband stored a list of Bajoran names in his shop, to which she suggests someone else put it there. Hearing the name Ches'so, she asks who it is and Odo replies he does not know and would like to talk to them. Odo mentions that her electricity was recently terminated and asks where she got the money for the bill. A loan from a friend, she says, but she intimates that her "friend" is married and will not embarrass him. Kira tells Odo she has found "Ches'so," which is really "Ches'sarro". Odo realizes he is responsible for Ches'sarro's death for divulging the name to Pallra and orders security to be stationed with the still unconscious Quark.
Once more Odo remembers prior events. He asks Quark, Kira's alibi for Vaatrick's murder, what the two of them were doing. Quark suggests that Kira was showing him her "credentials," at which point Odo knows the alibi is false: Kira nearly attacked Odo when she thought he wanted sexual favors. When he confronts her about paying Quark for an alibi, Kira reveals that she was committing a terrorist attack on the station. Gul Dukat enters Odo's office shortly thereafter and Odo tells him Kira is not the culprit in the murder.
In the present, the man who shot Quark incapacitates the officer guarding the Ferengi and begins suffocating Quark. Rom enters and saves Quark's life by screaming, gaining the attention of security forces. Brought to DS9, Pallra denies knowing the man, but Odo has confirmed that the two have been in frequent contact and she transferred a large sum of money into his bank account. Pallra has extorted money from the people on the list - Bajorans who collaborated during the occupation, to keep their identities private. When she declares her innocence in the murder case, Odo replies, "I know."
Kira comes to Odo in his office and asks how he knew. When he heard the list consisted of Bajoran collaborators, Odo realized that was how Vaatrick had money for tea during the occupation. Kira killed Vaatrick and Ches'sarro died at the hands of former resistance members, not Pallra. Kira murdered Vaatrick for being a collaborator. She never told him before because she was afraid it would affect their friendship. She asks Odo if he will be able to trust her again and he simply looks down at his desk, apparently unable to answer.