Synopsis by Hal Erickson
Michael Rennie, who earned his sci-fi/fantasy chops as the benevolent alien Klatu in The Day the Earth Stood Still, essays a far less benign characterization in this, the first episode of a two-part story. Rennie plays the titular Keeper, the curator of an intergalactic zoo comprised of monstrosities gathered from all over the galaxy (two of each). Careless Dr. Smith (Jonathan Harris) accidentally releases the Keeper's hideous monstrosities, who threaten to destroy the Robinsons' planet unless the family agrees to a set of frightening "conditions." Although we're not supposed to notice, sharp-eyed viewers will recognize several of the monsters appearing herein as "carryover" creatures from earlier Lost in Space episodes.