In this espionage drama, a Secret Service agent must discover who has been smuggling British arms into China. The prime suspect is a prosperous Chinese merchant-philanthropist and the agent thinks the merchant is working with the notorious Chinese guerilla warlord General Ling.
Two prospectors in Africa, Tony Cooper and Dalton come across a skeleton that has nearly been picked clean by vultures. They find a letter on the body addressed to a clerk in London named Wilkins . Cooper goes to Wilkins in London and tells him that his brother, whose body they had found, has left a map and a deed to a large diamond mine. Wilkins decides to go to Africa with Cooper to find the mine and, in order to speed up and finance their venture, they give a third interest to Carol Reade and her partner John Trevor), who operate a barnstorming airplane service. In Africa, close to the mine location, they are greeted by some tough gentlemen named Collins and Quincy who have terrorized the natives and lorded over the region, who quickly discover the reason for the party's mission. They join, unasked, in the race for the diamonds. The race is interrupted by the death of Trevor who is found knifed in his bunk.
James Martin and Carol Wall have plans to elope, but a fight with her father's solicitor ends in murder committed by an unknown third-party, and Martin is hunted for the crime, knowing the solicitor was alive when he left him. Carol refuses to speak to him, and he escapes on a ship to South Africa. There, he is the victim of an accident that disfigures his face, and he returns to England to clear his name, believing he won't be recognized. Other than by everybody who knew him, it turns out.
