Geoffrey Wedgwood secretly replaces an astronaut and Professor Wedgwood launches Geoffrey into space.

Professor Norman Wedgwood is the head of an experimental rocket group on remote Buchan Island in Scotland. His children, Geoff, Valerie and Jimmy visit him to watch the launch of his latest rocket, along with journalist Conway Henderson. When the pilot is taken ill, Jimmy finds himself taking his place on a mission to the Moon along with his pet hamster, Hamlet. After several harrowing hours in space, Jimmy, Hamlet and the rocket are finally brought down to Earth.