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For more links see fantasy & sci-fi links (under Babylon 5).
This was a spin-off of Babylon 5. Not nearly as good as that show (how could it be?), but still decent. The network really screwed it up and finally cancelled it after one season. It needed more seasons to develop, and JMS should've been given greater creative control.
Anyway, basically, after the Shadow War in B5, all the First Ones left the galaxy. But the Shadows had servants who stayed behind called the Drakh. We saw them a bit in B5, toward the end. Anyway, five years later, in the TV movie A Call to Arms (IMDb; Wikipedia), the Drakh attacked the Earth with a Shadow Planet-Killer, but were foiled. So they dropped a plague on the planet which would kill everyone within 5 years. Thus, the series Crusade was about a ship, the Excalibur, hunting all around the galaxy trying to find a cure... perhaps some records of some lost civilization that might've known something....
Clearly, a cure was eventually found, for we've seen further into the future on both B5 itself and other related things.... But this series never got a chance to find the cure before it was cancelled. Anyway, the Excalibur's captain was Matthew Gideon (played by Gary Cole, previously best known to me from American Gothic). Second in command was John Matheson (played by Daniel Dae Kim, who I'd later see in other stuff, most notably Lost). There was also a self-serving archaeologist named Max Eilerson, a technomage named Galen, a doctor named Sarah Chambers, and a former thief named Dureena Nafeel (who we kinda like), who was the last survivor of a race killed by the Drakh during the Shadow War. Um... anyway, maybe I'll say more if I ever get a chance to see the series again.