In the wake of the peace treaty with Cardassia, Sisko is excited about working with two Cardassian scientists who are assigned to help deploy a subspace relay in the Gamma Quadrant -- a project which, if successful, will allow communication through the wormhole for the first time. But Vedek Yarka warns that an old Bajoran prophecy predicts destruction of the wormhole, as three 'vipers' will return to their 'nest' in the sky. He deduces that the scientists are the vipers and the station must be their nest. Still, there are only two Cardassians arriving, and Sisko believes the project is too important to abandon. Later, the Cardassian scientists, Ulani and Gilora, arrive, and immediately put the crew at ease with their friendly manner. However, when they announce that another scientist will soon be joining them, Kira is concerned, believing this is the third 'viper' in the prophecy.
