On a weekend hunting trip, Moe, Larry & Curly Joe come across a clever mountain lion, who takes refuge in their cabin.

Two escaped convicts are found hiding in a rocket ship built by a renegade inventor, who forces them to become the crew for a trip to the Moon. Also on board, as inadvertent stowaways, are his assistant and his secretary; and none of them are aware that the inventor is actually a Lunarian explorer sent to Earth by the dying Lunar civilization.