Last Remains

Summary
An electromagnetic pulse causes stationwide failures, the destruction of a ship coming through the wormhole, and a shift in Bajor's rotational axis. Dax identifies the source as something inside the wormhole. While Sisko considers his options, which include collapsing the wormhole, a probe reveals the remains of a Romulan warship inside the wormhole. The vessel's artificial singularity is disrupting the wormhole. Dax, Kira, and O'Brien must retrieve the Romulan ship before another pulse destroys DS9.