The Heroes of Telemark (1965)

Synopsis
In this tale of espionage and adventure set during World War II, Norway has fallen under Nazi occupation, and a factory is producing "heavy water" (a key ingredient in the manufacture of atomic weapons), under the order of the German military. Knut Straud (Richard Harris), a leading figure in the Norwegian underground, joins forces with scientist Dr. Rolf Pederson (Kirk Douglas), who is working with British intelligence agents to destroy the factory in hopes of keeping the Atomic Bomb out of Axis hands. However, while originally Straud and Pederson are only supposed to infiltrate the factory as a reconnaissance force while awaiting British troops, the English army is forced to retreat from their plans, leaving the Norwegians to destroy the factory and scuttle a shipment of the "heavy water" all by themselves. Inspired by a true story, The Heroes of Telemark also features Michael Redgrave and Anton Diffring. ~ Mark Deming, All Movie Guide