A small time diamond merchant jumps at the chance to supervise the purchase and cutting of a large first class diamond. But when the diamond is stolen from him, he is blackmailed into pulling off a major heist at the Diamond Exchange, located at 11 Harrowhouse.
A popular member of the Oxford community is killed and nobody figure out why. A police inspector is called in from Scotland Yard and discovers there may be more to the victim than anyone knows.