During WW2, in Nazi-occupied Norway, most locals hate the Germans but a few collaborate with them. Norwegian Nicole Larsen is engaged to be married to the regional German commandant, Maj. Paul Dichter. Being on the side of the Germans has its advantages for Nicole, who is despised by most of the patriotic locals. Unknown to them is the fact that Nicole is a member of the Resistance, an agent of the British S.O.E. and has been sent to her native Norway to collect intelligence. Her relationship with German Maj. Paul Dichter is just a front, an excuse to be around him, his military plans and around German military installations without raising the Nazis' suspicions. She regularly passes the information she collects to a contact man in town, her optometrist, who passes it to London. However, after a few successful British air raids against secret German installations and after several sabotage actions against the local German garrison, the German commanders become suspicious of her. At first, her German fiancé and lover vehemently denies she could be a Resistance fighter and staunchly defends her in front of his suspicious superiors and colleagues. Later, however, he becomes suspicious of her himself and agrees to test her loyalty to Germany by setting up a trap for Nicole. Sensing danger, Nicole contacts London. Her London bosses decide to send a British commando, Capt. Allan Lowell, to rescue Nicole and possibly kill Maj. Paul Dichter.