| Director | Michael McCarthy |
|---|
In May 1940, as the German invasion of the Netherlands is under way, the British government decides to send a team to the Netherlands on board to secure stocks of industrial diamonds before the invaders can get to them.
According to this plan, two Dutch diamond experts, Jan Smit and Walter Keyser (Alexander Knox), with a British Army Intelligence officer, Major Dillon, are dropped by ship off the Dutch coast. They survive a German air raid and escape the attention of a suspicious Dutch policeman. Needing a car, they commandeer one driven by Anna, who is trying to commit suicide because she blames herself for the deaths of her Jewish fiance's parents. Anna turns out to be a member of the Dutch security forces and agrees to help the mission.
The four of them drive to Amsterdam where they meet Jan's father, Johan, at his diamond business house. Johan agrees to try to persuade other dealers to bring their diamonds later that day for transport to Britain. However, many of the stones are stored in a time-locked bank vault which cannot be opened for 24 hours because of the Whit Monday holiday, so they recruit Dillon's contacts, a Dutch resistance group, to break in.
Fifth columnist elements in the Dutch army launch an attack outside the bank but the group manage to break into the vault and recover the diamonds. Jan kills the leader of the fifth columnists, a Dutch army lieutenant. While the resistance fighters defend against the attack, the three agents and Anna make their escape. They drive back to the coast, dodging a German air attack on the way, but find that their boatmaster has been killed. They commandeer a tugboat to take them back to the waiting destroyer, but Anna elects to remain in the Netherlands and work with the nascent resistance movement.