It seems to be a normal day in Ops when O'Brien detects an unusual transporter signal. A strange version of Bareil Antos then materializes directly into Ops and takes a bewildered Major Kira hostage. He proves to be inoffensive (his disruptor is not even working), and he is finally convinced to try to make himself a new life on the station instead of fleeing.
Even though the mirror Bareil gets strange looks from all around, he begins to adjust himself to life on the station, and even Kira has a hard time sorting out her feelings for him. The two share more and more time together, and even though it is clear that the visitor is not a duplicate of the former Vedek Bareil, Kira is attracted to him. The man who didn't even think of spirituality in his former life pushes his interest as far as to try an orb experience.
When all seems to be unfolding for the better, the mirror universe version of Kira visits Bareil and, at that point, we learn that all of Bareil's previous behavior was only a plot to steal the Orb of Prophecy and Change and return to the mirror universe to use it to unite Bajor and act as joint leaders of a rebellion against the Alliance.
However, the following scenes show an ambiguous version of Bareil. He doesn't know where his loyalty lies any more, clearly influenced strongly by his "new" life and his orb experience. Quark is even able to notice that the man is tormented by something and warns Kira about that.
When Bareil goes ahead with his plan, Kira is waiting for him and reveals her disappointment by what she discovered. Even if mirror Kira arrives in time to save the game, Bareil finally decides against stealing the orb. Nevertheless, he still decides to go back to the mirror universe because he doesn't think he will be able to change lifelong habits at such short notice. He tells Kira that the vision he had was about a happy life on Bajor with her and that he really believed that could work for a time, but finally realized that he really belongs to the mirror universe.