“Apocalypse Rising” is episode one of season five of Star Trek: Deep Space Nine.
In the season four finale, “Broken Link”, Odo was judged by his people and turned into a solid. One thing that he remembered from his time in the Great Link during this was that apparently Gowron, Chancellor of the Klingon Empire, is a Changeling. Starfleet is going to send a team in undercover into the Klingon Empire with some prototype devices in order to cause the Changeling to reveal himself. Gowron is currently on a heavily protected station, so getting in will have to be through stealth.
The team consists of Worf, as well as Sisko, O’Brien and Odo (who is struggling to a degree with being a solid), the latter three all disguised as Klingons. They get to the station on board the Bird of Prey that Gul Dukat acquired in “Return to Grace”; getting out again will be a lot trickier.
Back on the station, Major Kira and Dr. Bashir have a discussion about the fact that she had Keiko’s baby transplanted into her in “Body Parts”. This is a bit amusing, especially when Kira says that the baby is all Julian’s fault. This is because, in real life, the baby is Nana Vistor‘s (Kira) and Alexander Siddig‘s (Bashir). So the conversation, when viewed from that angle, looks rather realistic.