London, 1908...the Olympics are taking place in London and John Baxter Taylor, Jr., an African American, will be competing in the medley relay race. However, someone does not want John participating in the Olympics and is threatening bodily harm if he competes. John's American friends, Gatlin Evers and his sister Callie, approach the Zane Brothers Detective Agency, requesting both protection for John and investigation into who is threatening the athlete. Seth Zane and his brothers accept the assignment which proves to be a dangerous one...both for the brothers and the visiting Americans.