Captain Royd Frobisher receives a top-secret government mission - to go to the British colony in West Africa, find a diamond mine in the jungle where kidnapped Crown citizens are working, free the captives and collect strong evidence against the organizers of the illegal enterprise. Just before sailing, Royd's ex-fiancée, Isabelle Carmichael, comes to him and demands to take her with him to Freetown. She and her relatives assume that Isabel’s cousin, Catherine Fortescue, is languishing there in captivity. Royd agrees to take Isabelle, hoping to win back her love and restore the relationship. On the high seas aboard the Corsair, in the tropical jungle and the ballrooms of London's Mayfair, a true drama of passion is played out, which ends in a brilliant climax - the rescue of prisoners, the revival of great love and a series of long-awaited weddings.