When Norwegian resistance leader Lieutenant Erik Bergman reports the location of a German V-2 rocket fuel plant, the Royal Air Force's 633 Squadron is assigned the mission to destroy it. The plant is in a seemingly-impregnable location beneath an overhanging cliff at the end of a long, narrow fjord lined with anti-aircraft guns. The only way to destroy the plant is by collapsing the cliff on top of it.

Industrialist François Delambre is called late at night by his sister-in-law, Helene Delambre, who tells him that she has just killed her husband, André. Reluctant at first, she eventually explains to the police that André invented a matter transportation apparatus and, while experimenting on himself, a fly entered the chamber during the matter transference.