Prince John, the despot ruler of N.O.T.T., invites Rocket Robin Hood to a challenge against the Sheriff's cruel and burly deputy, Titanor. If Robin succeeds, Prince John will lower the taxes for the peasants of N.O.T.T.
The Sheriff of N.O.T.T. builds a time machine to send Rocket Robin Hood and Little John back to earth, specifically twelfth century England, to deal with his ancestor, the Sheriff of Nottingham.
Ming, the Warlord of Saturn, hits Little John with hypnotic gas. With Little John under his control, he launches an attack on Sherwood asteroid with the devouring machine OxyVac.