An alien zookeeper arrives, and the Robinsons are suspicious of the way he views them as verminous life forms, rather than sentient beings. The Keeper decides to add Will and Penny to his menagerie, and tries to trick them into one of his cages, even putting on a facade - which falls easily when he's frustrated - of being friendly and fatherly. Hoping to steal the Keeper's ship, Dr. Smith sneaks on board, but accidentally lets all of the animals loose.