Dax returns from the Gamma Quadrant in her runabout with a woman O'Brien recognizes as Vash. Although the crew is unaware of his presence, Q - a nearly omnipotent prankster - has also stowed away on the runabout. Vash explains that she has spent the past two years in the Gamma Quadrant, but she describes her method of getting there as a "private matter."
Soon after Vash's arrival, the station begins to experience power drains similar to those experienced by Dax's runabout. In the meantime, Q appears to Vash, apparently infatuated with her. Q was the one who transported Vash to the Gamma Quadrant two years earlier, but now she wants nothing to do with him, much to Q's annoyance. When Dr. Bashir asks Vash out for dinner, a jealous Q uses his powers to send Bashir off to sleep. Meanwhile, Quark arranges to auction off various items Vash has found in the Gamma Quadrant, most notably an unknown but extremely valuable crystal of some kind, and in the meantime O'Brien spots Q and recognises him immediately, since they met during O'Brien's tour of duty on the Enterprise.
O'Brien warns Sisko of Q's presence and the likely cause of the power drains. Q denies any wrongdoing, although he offers no alternative explanation. As the power drains become more severe, some type of gravimetric field begins pulling the station toward the nearby wormhole. Q challenges Sisko to a boxing match on the Promenade, and they suddenly are wearing antique-style boxing costumes. A few punches are thrown, and Q is shocked when Sisko knocks him down. "You hit me! Picard never hit me!" Q exclaims. Vash and Quark go about their auction and the crystal receives bids in excess of one thousand bars of gold-pressed latinum.
Casually joining the bid process, Q ups the ante on Vash's crystal to 2500 bars before bidding one million. Soon after, however, the source of the gravimetric field and power losses is found to be the crystal. The crystal is beamed into space before it can destroy the station, and once outside, it reveals itself to be a mysterious life form and travels into the wormhole. After the trouble is over, Bashir finally awakes. Unaware of what has happened, he yawns and tells Dax that he feels like he has been asleep for days. A bemused Dax gives him a strange look to which Bashir replies "What--did I miss something?"