Plot summary
Cardassian professor Natima Lang (Mary Crosby) arrives at Deep Space Nine with her students, Rekelen and Hogue — political dissidents intent on reforming the oppressive Cardassian military government. Lang and Quark were once lovers; Lang ended the relationship after Quark betrayed her trust, and she now wants nothing to do with him, but he still has feelings for her.
When Lang sees Garak at Quark's bar, she panics, guessing he will inform the Cardassian government of their presence. In the guise of a conversation about fashion, Garak hints to Quark that Lang's radical beliefs and companions are likely to lead to her death. Quark offers Lang his assistance, but she refuses, not trusting him to care about anyone but himself.
Meanwhile, a Cardassian warship arrives and threatens the station. Garak explains to DS9' s senior staff that Cardassian Central Command wants Hogue and Rekelen, whom he describes as terrorists, handed over.
Quark offers Hogue and Rekelen a contraband cloaking device to help them escape, on the condition that Lang stay with him. Lang has an argument with Quark, during which she accidentally shoots a phaser at Quark, stunning him. Horrified, Lang finally admits that she still loves him and Quark finally manages to convince her to stay.
Lang and her students are arrested by security chief Odo: the Bajoran government has agreed to turn them over to the Cardassians in exchange for the release of several Bajoran prisoners. A former rival of Garak's, Gul Toran, tells Garak that Central Command wants the prisoners dead; in exchange for killing them, Garak will be allowed to return to Cardassia.
Quark convinces Odo to release Lang and her students. Garak greets them at their ship, where he laments that he must now kill Quark as well. Toran appears, revealing that he only used Garak to learn Hogue and Rekelen's whereabouts; the offer of a return to Cardassia was a lie. Garak shoots him and allows Lang, Hogue, and Rekelen to escape. Lang convinces Quark to let her leave, promising to return to him when her work reforming the Cardassian government is done. Quark sadly lets her go.
Once she leaves, Quark asks why Garak shot Toran, and Garak asks why Quark let Lang go. "I had no choice — I love her," Quark says. Garak replies, "And I love Cardassia, which explains what I did".
Credits
Adapted from Wikipedia contributors, Profit and Loss (Star Trek: Deep Space Nine). Paragraphs and formatting adjusted; illustrations, reference markers, block quotations and non-story material omitted.