Dr Smith and Will encounter a wild ginger man named Captain Tiabo. The man and his bird-like companion label the two ‘invaders’. They are escorted to a cave Tiabo refers to as his ‘headquarters’ and taken prisoner. Later Captain Tiabo says he must briefly leave to report his findings to his superior, General Undos.
While he is away, Smith helps himself to a drink left on the table. After several sips he deems it “a delightful beverage”. General Undos interrogates Will and Dr Smith via a video link screen. He reveals he has a secret super weapon. Later another leader of an intergalactic army is seen speaking on the screen as well. Will notices Captain Tiabo, General Undos and the Alien Army leader all look strangely alike.
Smith has fallen under the spell of the ‘delightful beverage’ and observes – “There’s something wrong with this drink. Once you start you can’t stop.” When he and Will eventually escape the cave, Smith takes the whole drink cask with him.
After some hours, Dr Smith throws the empty keg away. When he does this it explodes. The robot analyzes the drink and concludes Smith has been drinking liquid high explosive. He warns everyone must stay a minimum 50 yards away from him as Dr Smith is now a walking bomb.
Meanwhile the Robinsons are busy trying to repair their force-field before Tiabo and General Undos launch their claimed secret weapon. Dr Smith is quarantined from the family’s campsite but complains he is so lonely. When Maureen remarks, “Poor Dr Smith“ the robot cautions “It must also be remembered he is a dangerous Dr Smith.”
Will travels to Captain Tiabo’s cave seeking an antidote for Dr Smith. He walks in without Tiabo realizing he is there. Will sees Captain Tiabo impersonating so-called General Unos and the Alien Army leader in video transmissions. Will confronts Tiabo and tells him he can stop pretending as he knows there is no alien army but rather it’s just him living alone on the planet.
Will assures Tiabo his family are no threat to him. He gets the antidote pills from Tiabo and runs back to give them to Dr Smith. He arrives just in time as the robot has connected Smith to a detonating rig. Will saves Dr Smith and ends the robot’s plan to blow up Smith to ensure the safety of the Robinsons.
Ps. This episode was an acting tour de force for Wally Cox. He played all three parts of Captain Tiabo, General Unos and the Alien Army Commander.
Cox was also the author of a number of novels and books for children. He died at the age of 48 in 1973.