After spending the day fishing with his father at the cannery wharf, Finn likes to escape to a secret cove to go swimming with the seals. When he discovers a young seal trapped in a fishing net, Finn frees the creature, then furtively catches salmon to feed the seal while it recovers from its ordeal. A bond develops as the seal grows stronger, and Finn wishes that it could remain on land with him and be his friend.

When a mysterious girl named Sheila appears in the village and the fishermen begin to whisper that she is actually a selkie, one of the shape-shifting seal people of Celtic myth, it seems as though Finn’s wish has been granted. But could the old fishermen really be right?

Andrea Spalding intersperses her text with verse that illustrates the seals’ mesmerizing underwater world: “Frantic splashing / seals dashing / churning, thrashing.” Unfortunately, her prose is stilted and spare in comparison, and puts the reader at a distance. This effect is magnified by Pascal Milelli’s illustrations, which are beautiful but contain muted tones and abstract arrangements that may not immediately appeal to children.

Though the old fishermen predict Sheila’s presence will bring bad luck to the community, the fish have become more plentiful since her arrival. And when, despite Sheila’s warning, Finn ventures out to sea during a storm, it is she who goes door-to-door in an effort to organize a rescue, finally diving into the sea when all else fails.

The storm scenes are skilfully rendered, and Milelli’s pictures are particularly vivid at this point. The story’s element of magic, only vaguely alluded to until now, is finally made clear when Sheila returns to seal form upon re-entering the water. Finn’s life is saved, but at a cost.

The book culminates in a final, satisfying image of Finn and his father fishing again the following spring, tossing salmon to the seal that always swims alongside them.