The leader of all things spiritual on Bajor, Kai-Opaka hints to Sisko she would like to take a journey into the wormhole (Remember, Kai-Opaka has never ventured off of her planet her entire life let alone into the newly discovered wormhole and a potential new galaxy trip) and also hints it is the "Prophets" who are inspiring her to take this trip.
Going along for the ride with Sisko and the Kai is Kira and a giddy Doctor Bashir.
This episode quickly steers away from a spiritual episode (fulfilling the Prophets will) and into a macabre Twilight Zone-esque episode. DS9 was dedicating screen time to zombie-like creatures WAY before the Walking Dead.
Notice: Sisko's demeanor during a life or death struggle onboard a dying shuttlecraft (okay they now call these craft "runabout's). Who really acts like that? I mean he acts as if he's ordering a meal in a drive through.
Notice: Sisko is much more than the Commander of a space station and a cool cucumber flying a roundabout. He is also a total beast in hand-to-hand combat. I mean he is awesome. I think he could kick Picard and Janeway's rumpus. Kirk and he would have a heck of a duel!
Star Trek always delves into civil war-type episodes where there are two passionate sides of an issue, idea or predicaments. Get ready for this full force. The one story craft Star Trek reverts to if the two sides cannot find compromise is: utter destruction.