Captain Bob Bright and his old space-salt friend Gaffy are seeking a cargo for to carry in their cargo spaceship. They find a young woman being assaulted by ruffians and straighten out the gang. The woman is June Rogers. She and her brother, Stan Rogers, inherited a treasure map from their father. June wants Bob to take them to the asteroid belt to follow the map. Captain Bright agrees to the term of a third for himself and Gaffy. They catch the attention of some space claim-jumpers that follow them.