Zygon: When Being You Just Isn't Enough

They've been stranded on Earth for 20 years, so Zygon commander Kritakh, and his second, Torlakh, have had plenty of time to re-create their world. The trouble is that Kritakh, aka engineer Mike Kirkwood, has lost his sense of purpose. Can Torlakh, aka mass murderer Bob Calhoun, get him back on track.