Philip Rhayader lives alone in an abandoned lighthouse on the desolate Great Marsh of Essex. One afternoon, a hauntingly beautiful child, Fritha, visits Rhayader, bringing with her an injured snow goose. At first Fritha is scared of Rhayader, with his sinister hump and crooked hand, but he is gentle and kind and Fritha begins to visit regularly. When the snow goose departs for home, Rhayader is left alone again.

The following winter, the snow goose and Fritha return to the lighthouse. Time passes and one year Fritha is frightened to discover her feelings for Rhayader. But this is 1940 and Rhayader is setting sail for Dunkirk to help the soldiers trapped on the beaches. Fritha never sees Rhayader again. But the story of the saviour with the snow goose passes from soldier to soldier and into legend . . .