Popeye and Olive are touring a museum when they accidentally launch a rocketship to Mars. Olive escapes, but Popeye gets to Mars, where he is attacked (by a group led by Bluto) that was preparing to invade Earth. Fortunately, Popeye has a can of spinach handy, so he can save the Earth (turning most of the Martian war apparatus into amusement park rides)..