The Robinsons find themselves unable to understand the electronic language of a space family - the first of many colonists, from the planet Tauron,who will arrive to settle on the planet,travelling on a Tauron maser beam through space. Will befriends the aliens' son, but the Tauron boy falls ill and Will stays with him overnight in a cave, while the alien parents and the Robinsons wonder what happened to their boys. Smith tries to convince everyone that the aliens are holding Will captive.