Missing in Action by Peter David
Following the dramatic conclusion of AFTER THE FALL the crew of the USS Excalibur are lost in space, somehow thrown headlong into the mysteries and dangers of the distant Andromeda Galaxy -- and no sooner do they arrive than they are caught up in the middle of a genocidal interstellar war. Now Captain Mackenzie Calhoun -- who himself grew up a freedom fighter battling the forces of an aggressive conqueror -- must decide where his true loyalties lie. Should he save an oppressed race from certain destruction? Or ally himself with the violent alien warriors who offer the only hope of getting Excalibur home again...