The mirror-universe Ezri shows up demanding that Quark bring a cloaking device to the Regent Worf in exchange for Grand Nagus Zek, who went to the other side in search of business opportunities. Quark enlists Rom's help in stealing one of those devices from a docked Klingon Bird-of-Prey, which they hide by cloaking the cloaking device. When they reach the habitat ring, they avoid questions from a confused Benjamin Sisko and an impatient General Martok when they noticed them idly staring at a bulkhead. They manage to get the device to mirror Ezri, and are forced to transport to the mirror universe when Martok discovers the theft. Upon arrival at the alternate Deep Space 9 (now called Terok Nor), they meet Vic Fontaine, who is not a hologram in the mirror universe (and then shot by Bashir).
The three are held captive, as the Rebellion cannot allow the Klingon-Cardassian Alliance to gain such cloaking technology. They are rescued by an alternate version of Brunt, who brings them to the Regent, where it is revealed that the alternate Kira Nerys had planned this all along. Quark and Rom discover that Kira and Ezri are lovers and are then imprisoned.
Zek tells the two Ferengi that he stole the plans to the multidimensional transporter so he could arrange business agreements with this universe, but the plan backfired when he was caught.
Rom is forced to install the cloaking device on the Regent's ship, but despite his cooperation, he and Quark are still sentenced to die at the hands of mirror Elim Garak. Ezri, however, injects Garak with the poison meant for Quark and Rom; she reveals her motivations to be both a grudge against Garak and regret over the death of Brunt.
The empire attempts to use the cloaking device on the Regent's ship, but it turns out that Rom had sabotaged the device to drain the power grid, and the ship is easily overtaken by the Defiant, forcing Worf to surrender to the Rebels. The Rebels bring the three Ferengi (and Zek's servant, Maihar'du) back to Terok Nor, where a Leeta who never married Rom comes to "debrief" Ezri. Rom then expresses his dislike of the alternate universe.