A first-time captain leads a convoy of allied ships carrying thousands of soldiers across the treacherous waters of the "Black Pit" to the front lines of WWII. With no air cover protection for 5 days, the captain and his convoy must battle the surrounding enemy Nazi U-boats in order to give the allies a chance to win the war.

On a winter morning, a mother goes to waken her son Heinrich; his bed is empty. She leaves her flat to find him. The neighbors' door, with a Star of David painted on it, is ajar, the furnishings in disarray, the family gone. She asks passersby, runs to the police then on to the rail yard. Flashbacks show that Heinrich and the neighbors' son Paul are six years old and best friends. Paul's family's deportation is expected soon; Heinrich's mother tells her son that they're going to Toyland. Heinrich wants to go with them, has a bag packed, and listens for their departure. His mother realizes he's joined them, and her resolve becomes more urgent. Will she arrive in time to save Heinrich?

The story of the miraculous evacuation of Allied soldiers from Belgium, Britain, Canada and France, who were cut off and surrounded by the German army from the beaches and harbour of Dunkirk between May 26th and June 4th 1940 during World War II.