Jumpgate #42 - Divided Loyalties
Vera Wylde and Jessie Gender take up residence on Babylon 5, taking in one episode at a time. Season 2, Episode 19, Divided Loyalties - A character not seen on the station in quite some time returns, and brings word of a dangerous sleeper agent on board Babylon 5... an agent who doesn't even know that they're a sleeper agent.