Jack Hawkins is starred as a gruff, intensely dedicated Scotland Yard superintendent. Working as much by instinct as through scientific methods, Hawkins and rookie sergeant John Stratton tackle the case of a string of unsolved safecrackings, committed by the elusive Richard Leech. This Dragnet approach gives way to suspense as robbery leads to murder. A neat surprise twist caps this finely honed example of British moviemaking know-how. The Long Arm was released in the U.S. as The Third Key.