The team follows a stranded time pirate to Mississippi, 1863, and discover that the man has unleashed a bioweapon that transforms humans into zombie-like creatures. If they don't stop the zombies from overrunning Grant's army, history will be altered beyond repair.

The team detects a timequake in 1874 and travel to Colorado, where they meet their former ally Jonah Hex. Jonah is on the trail of an outlaw, Quentin Turnbull, and the team realize that Quentin is the reason for the timequake. Meanwhile, Amaya gives Mick advice on controlling his rage, and Martin has memories of a woman he doesn't know.