Dr. Bashir and Jadzia Dax respond to a planet's calls for help in the Gamma Quadrant. However, when they land the see that the place has been a hellish mess for a long time. It seems that this once- great civilization offended their Dominion overlords and as punishment, the Dominion released a horrible virus upon them. This virus doesn't kill the people instantly but causes lesions. Eventually, and there's no predicting when, they proceed to a phase called 'the Quickening'-- with intense pain and death. However, the folks on the planet, despite the automated distress call, don't seem terribly concerned about finding a cure--they just accept that they are all going to die and that is that. In fact, instead of doctors, they have folks like Trevean (Michael Sarrazin) whose job it is to help expedite their deaths...peacefully. Can the landing party manage to come up with a cure--especially when the disease is so incredibly resistant to treatment?
This is an incredibly sad episode--certainly not what you could call a 'feel good' show. Fortunately, it IS still well worth seeing and is a wonderful example of just how amoral and nasty the Dominion can be.