Roger Willoughby is a renowned fishing expert, who, unbeknownst to his friends, co-workers, or boss, has never cast a line in his life. One day, he crosses paths with Abigail Paige, a sweetly annoying girl who has just badgered his boss into signing Roger up for an annual fishing tournament.
A girl owns a horse, and hires a boy as a trainer. The horse enters a race and is injured. The boy takes job at another stable and is semi-seduced by the stable siren. The girl finally rehabilitates the horse then enters it in a big race.
While in London trying to nab several fugitives who stole a million dollars from a U.S. Treasury vault, American federal agent Dennison (Dennis O'Keefe) assists Scotland Yard Insp. McClaren (Philip Friend) in his search for a missing atomic scientist (Paul Hardtmuth). The detective duo discovers that the key to solving both cases may rest with the scientist's daughter (Margaret Sheridan) and her fascinating diamond.
An idealistic United Nations official learns the harrowing truth about war when she falls in love with an American officer charged with the evacuation of civilians. As hostilities escalate, the officer and his small detachment are left to hold the line until allied forces can be brought into action.