Professor Bump makes a great discovery and becomes invisible.; An escaped POW turns out to be a spy.; Two stuntmen at a circus are killed in staged accidents.; Two escaped convicts join German saboteurs.; Destroyer 171 stands ready to back a Commando raid with her mighty guns.; The Unknown is on a mission to recover stolen military papers in North Africa.; The Kid Patrol buys an old brass key at an auction and finds a Martian.; A boxer is shot and killed during a match.; A masterpiece of a strategic chart is blown out the porthole.; Windy is investigated by the Relief Board.; Cupid uses a sharp pointed arrow on a track runner to make him go faster.