"It's not," admitted Martha, frowning slightly when Liz pulled back from the door. "But we can survive them if we work together."

That was how they'd managed to get through the zombie invasion, after all. It hadn't been easy and it hadn't been without casualties, but Martha - who had seen her home planet reduced to ash by an alien tyrant and watched her race rounded up into slave camps - knew that it could have been much worse.