Gideon and Lochley must prevent a doomsday cult from killing everyone at a virus conference on Mars.

In an attempt to understand the nature of the Drakh virus better, the Excalibur is sent back to Earth's orbit for a top-secret special pick up. Familiar face returns. The show ends on an open ending.

The Making of Crusade - a behind-the-scenes featurette

Forging Excalibur - learn about the starship from the inside out