Two children named Gracie Jenkins Helen Pearce and Daniel Pender Max Rennie are best friends living on the island of Bryher. They love sailing the wooden boats they craft from the beaches, but their favorite craft is carried by the tide into a forbidden bay, the home of a local hermit known as the Birdman Paul Scofield. The elders and many locals mistrust him, partly because he was born on the nearby island of Samson, whispered to be cursed. On stormy nights, the Birdman crosses to Samson and can be seen signaling with lanterns out at sea.
Their curiosity leads them to the Birdman’s beach, where they discover the missing boat washed up on the sand, bearing a message written in stones left by the hermit. Daniel adds his own note of thanks and the children reveal their names. In time, the Birdman sends them a carved seabird as a gift, which the kids hide at Gracie’s house.
Life on Bryher is rugged and simple. The villagers survive on fishing and cultivating their own produce. Daniel’s father is harsh and struggles to feed his seven children. Gracie’s parents, Clemmie Jenkins Helen Mirren and Jack Jenkins David Threlfall, are more supportive; Gracie is eager for an education, while her father places less value on schooling, reflecting the different paths before them. The local school, run by Mr. Wellbeloved Jeremy Kemp, struggles to keep the children focused as tensions rise with the looming war.
Daniel and Gracie eventually meet the Birdman in person. They learn he is kind, gentle, and profoundly deaf. He shares a childhood tale: when he was a boy, a group of narwhals were slaughtered on Samson for their valuable horns, and the ship carrying their horns to the mainland was sunk with the Birdman’s father aboard. A cascade of misfortune follows—illness, failed crops, and the departure of islanders—until the Birdman’s hearing is taken by the continuing curse of Samson.
Daniel proves adept at carving, and the Birdman teaches him the craft. One day the children hear of a large amount of timber ashore that many islanders rush to claim, hoping to stash it before outsiders arrive. As they search the shores, they coax Gracie to let them look in her attic, where they find nothing but the carved seabird, which Daniel recognizes as his own work. The family’s pride grows as the seabird is proudly displayed in their home.
With the First World War underway, Gracie’s father joins the Navy, leaving Clemmie to manage the home front. Gracie and Daniel take the boat out themselves when the weather turns foul, and a thick fog leads them to unintentionally land on Samson. They discover the dry well, the graves of the old islanders, and one narwhal horn. When they return, Gracie’s mother fears they have brought a curse back with them, while the Birdman arrives with gifts of produce and goodwill to help them cope.
After a fierce storm, the three friends discover a beached narwhal and attempt to return it to the sea, but it is too heavy. The narwhals gather in the bay, and the Birdman senses that the Samson curse will rise again if they do not intervene. Daniel’s oldest brother, along with some local youths, burn the Birdman’s cottage under the mistaken belief that he is signaling to enemies. They witness the coming of the narwhals and the whales, and the village is stirred to violence.
In a turning point, the Birdman’s true purpose becomes clear: he has been trying to keep ships from running aground and to prevent the island from being overwhelmed by the curse. The community finally listens to his warning, and the islanders unite to guide the whales away from the dangerous rocks. With the truth about Samson revealed, the islanders work together to restore balance and safety.
Daniel leaves the Birdman watching the sea, and when he returns in the morning, he finds the Birdman gone, never to be seen again. He sails to Samson and discovers that the well is full again and plant life is returning. Later, a naval boat arrives with Jack Jenkins on board, found alive at last. The Samson curse lifts as the islanders come together in celebration, and Gracie, Jack, and Clem return home, their lives forever changed by the summer’s events and the quiet wisdom of a mysterious, deaf hermit who refused to abandon them.
