Following the attack on Earth by the Drakh, a plan is hatched to save it. Excalibur, a new vessel, is sent out to find a cure for the plague, and the man for the job is Captain Matthew Gideon. His first act is to capture one of the Drakh and get him to tell him what he can. Written by
Did You Know?
According to J. Michael Straczynski
's posts on the internet the opening of the first episode aired, "War Zone", was required by TNT to open with a fistfight. Later in the episode, the Senator briefing Gideon has a line to the effect of, "We've had to make a lot of compromises to get this thing off the ground" - literally about the Excalibur's mission, but also a line J. Michael Straczynski intended as a comment on the series itself. See more
The alien forces that attacked Earth struck without reason or provocation. Although they were driven back by our forces, on their way out, they left behind a biogenetically engineered virus that has completely penetrated the atmosphere. As a result, Earth has been quarantined. Repeat: Earth has been quarantined.