"Lemmy" the life-emulating robot returns to the zoo from Mars with an unwelcome visitor: a space squid which bursts out of his chest compartment, damaging him. After the squid immobilizes Mort with a phlegm-like substance, the penguins, lemurs, and Lemmy's head begin to hunt it down in order to protect the zoo and ultimately the planet from further invasion. Now larger in size, the space squid soon renders each penguin and lemur immobile. The alien is ultimately defeated by Lemmy, once his body had reconfigured itself through an automated process, using a combination of dance and fighting moves under the verbal direction of Julien and Skipper.