Jerry, fed up with Tom's harassment, decides to become a mouse astronaut and go off into space, where there are no cats. He packs his valise. Tom sees him leaving and tries to keep him from going by shooting him, striking him, and blowing him up with a bomb. Jerry goes to the astronauts' training center, takes a series of tests, and is declared fit for service. Meanwhile, Tom has become an alcoholic tramp. He hides in a pipe and soon finds himself being shot into space on a rocket. Tom gets into the cabin and harasses Jerry, who's inside. Tom is ejected and reaches another spaceship whose astronaut is a Soviet dog! Tom is hit by a shower of meteorites and falls through space, landing on the ground after a dizzying descent. There he finds Jerry, proudly sporting an astronaut's license. Tom sets it on fire. Jerry starts to chase him, and Tom takes to his heels.