Alison Dowland is about to marry her childhood sweetheart, Joe, when his regiment is recalled to battle, and American soldiers descend on the tiny Cornish harbour of Porthallack to prepare for the D-day landings. Excitement is high as the villagers prepare to welcome their allies, but to her dismay, Alison falls in love with American Chuck Bartlett. Amidst an agonising personal decision, she is also caught up in espionage, endangering herself and her sister.