برده‌های مخفی

Businessmen Felix Gane and John Leval require a ruthless associate to help them take advantage of slave labour in the Congo rubber industry. George Marsden Plummer, who overhears their plans while burgling Gane's house, introduces himself and is duly judged to be the man for the job. He arrives in the Congo accompanied by three roughnecks — Sam Mitt, Pete Carron and Nick Jute — and immediately wrests control of the rubber plantation from its kind-hearted manager, Will Mann. Realising that he's at the mercy of criminals, Mann escapes into the jungle but is recaptured, wounded and imprisoned. Managing to pass a letter to his faithful servant, Jim, he sends the man away to travel to England for help. Weeks later, Jim's journey ends at Baker Street and Sexton Blake takes up the case.