Captain New Eyes travels back in time and feeds dinosaurs his Brain Grain cereal, which makes them intelligent and non-violent. They agree to go to the "Middle Future" in order to grant the wishes of children in New York City. They are to meet Dr. Bleeb of the Museum of Natural History, but get sidetracked with their new children friends and run into the Captain's evil brother, Professor Screweyes.

Some time after the Mousekewitz's have settled in America, they find that they are still having problems with the threat of cats. That makes them eager to try another home out in the west, where they are promised that mice and cats live in peace. Unfortunately, the one making this claim is an oily con artist named Cat R. Waul who is intent on his own sinister plan.