Synopsis by Hal Erickson
Veteran movie heavy Torin Thatcher guest stars as The Trader, an intergalactic con artists who arrives on the Robinsons' planet in a ship full of attack dogs. As a means of drumming up business, the Trader conjures up a storm which destroys the Robinsons' food and water supply. Recognizing a kindred spirit when he sees one, conniving Dr. Smith persuades the Trader to take him in exchange for supplies; the deal is that Smith will become the Trader's slave--but only after a period of 200 years! Unfortunately, the good doctor hasn't read the fine print of the Trader's iron-clad contract. This episode marks a reunion between actor Torin Thatcher and director Nathan Juran, who'd previously worked together on the 1957 fantasy film The Seventh Voyage of Sinbad.