HOLMES IS HIRED TO PROTECT A PRECIOUS DIAMOND WHICH BELONGS TO RICH LADY. HOLMES SWITCHES THE REAL DIAMOND WITH A FAKE ONE. LATER, WHEN THE FAKE DIAMOND IS STOLEN, HOLMES SEARCHES FOR THE THIEF. STARRING BASIL RATHBONE, NIGEL BRUCE, DENNIS HOEY, RENEE GODFREY, ALAN MOWBRAY.