In the bleak Norwegian midwinter of 1943, a group of resistance fighters manages to destroy machinery used by the Germans to make "heavy water", a key ingredient in building atomic bombs.
The exercise, labeled Operation Grouse, was one of the most audacious raids of World War II, carried out by four handpicked commandos parachuted into German-occupied Norway.
It was the plot of a Hollywood movie called The Heroes of Telemark, starring Kirk Douglas and Richard Harris, but in fact, British television presenter and survival expert Ray Mears claims the film was a pale imitation of the true story.
Mears and a team of serving Royal Marines and Norwegian troops follow the grueling campaign the men underwent 60 year later. He demonstrates their courage as they struggled with freezing conditions and minimal rations, to survive four months on the brutal Hardanger Plateau, site of the Norsk Hydro facility at Vemork.
As he retraces their steps, Mears says that the Hollywood film missed the point of the story; that the men's incredibly tough survival skills and mental tenacity in the sub-zero temperatures, dragging their heavy kit across more than 100km through deep snow and fierce winds, made them the real heroes of Telemark.
The Real Heroes of Telemark tells their story in three parts.
Part three has the surviving heroes of Telemark recall how they carried out one of the most daring raids of World War II; blowing up the power station and stopping Hitler's atomic bomb programme in its tracks.