Provides an account of Stopwatch/Gold, a joint Cold War operation between the CIA and Britain's Secret Intelligence Service conducted from a tunnel under the Russian sector of Berlin in an effort to gain information about the planned actions of the German Red Army.

'The stuff of which thriller films are made' -- Our man in Vienna -- Smoky Joe's -- Black Friday -- The human factor -- 2 Carlton Gardens -- Agent 'Diomid' -- Operation stopwatch/gold -- 'Kilts Up, Bill!' -- Digging gold -- Turning on the tap -- Chester Terrace -- 'A bonanza' -- Fingers crossed -- 'It's gone, John'.