At the height of the Cold War, a Soviet Yak-28P Jet Fighter Interceptor fitted with the latest top secret radar interception system, crashed into a Lake in the British Sector of West Berlin. Whilst the British military mount a salvage operation, the Russians make an armed incursion into the British Sector with the aim of preserving their aircraft's secrets. The Russians plan to retrieve the secret radar component and activate a sleeper agent at the British HQ, and send top KGB Agent Alexander', into West Berlin. A Military Policeman and his German girlfriend are blackmailed into assisting an East German Stasi intelligence cell, and after recovering the aircraft's secret radar component for them, they are killed. Wolf, a detective from the Special Investigation Branch is brought in to carry out a covert Investigation and is involved in a gun battle with a Stasi Agent in the American Sector, resulting in the death of four US CID agents and the Stasi Agent. A joint SIB, US CID and Intelligence task force is set up to track down the enemy agents, but amidst the gunfire and explosions, can Wolf prevent the Soviets retaining their technical superiority.