After being fired from his job at a grocer, George, gets a job as a stableboy at a local stud farm run by the Fleming family. He befriends the horse Hotspur who is a favourite to win the Melbourne Cup, and develops a strong whistle which is used to make the horse run fast.

An evil scientist, Parta Beno, who has been found guilty of imprisoning and reducing in size inhabitants of various planets. As punishment he is exiled to a remote asteroid, with the only amenities being a crude laboratory. All the specimens that Parta Beno collected were sent back to their home worlds by the World Council, except those few that the Council had no knowledge of, let alone any idea about the planets from whence they came. The hand-picked crew of 'The Interpretaris' were given the mission of returning these aliens to their home planets.

The diggers and their officer, who has fallen for a nurse at the hospital, are subtly manipulated by a British intelligence officer to assist in passing false battle plans to the Germans. Given leave in England, they end up billeted at a country house and offered barley water instead of the home-brew they anticipated.