The Wallace Boys leave Africa and go to the United Kingdom. They immediately fall into an adventure in London, giving Scotland Yard a helping hand along the way! This story is set in the West End Theatreland of London and South Cornwall.A leading actor in Agatha Christie's world-famous, long-running play – The Mousetrap – helps 'lost' youngsters on the streets of London. But is he all that he appears to be? The Wallace Boys assist a young boy in finding out what happened to his elder brother who has disappeared under very mysterious circumstances.