Tamsin looks as if the lighthouse weather has been slowly writing itself across her: salt has roughened the bridge of her nose and the backs of her hands, and wind has left her cheeks permanently pink. Her dark hair is usually caught in a practical knot, with loose strands stuck to her forehead by mist. She moves with a careful, rocking steadiness, feet placed as though every floor might be slick. A surprising detail for a solitary keeper is the small collection of brightly painted paper birds she folds from old shipping notices and hangs in the lantern room.

Tamsin is quiet but not timid: she dislikes being the center of attention, yet will argue relentlessly when someone proposes an unsafe crossing. She is meticulous with records and unexpectedly playful when folding paper birds. In company she listens more than she speaks; under pressure she becomes brisk and exacting, then later apologizes by quietly fixing whatever the argument disrupted.

Tamsin grew up in the fishing harbour of Gullcross, the daughter of a net-mender and a tide pilot. At seventeen, she joined her mother on a night crossing through a sudden fog. Their boat struck a reef after the lighthouse lamp failed; Tamsin survived by clinging to a marker buoy until dawn, while her mother and two deckhands were lost. She apprenticed herself to the old keeper, Orvek, and eventually took the post, determined that no ship should be left without a warning light. Orvek died two winters ago, leaving her the lighthouse and a logbook whose entries go back generations. She still writes down every vessel that passes, including ships that no one else admits to seeing. Three nights ago she vanished. The lamp has continued turning, though its oil supply should have run dry, and the harbour's boats have begun returning with their nets full of black, glassy weed.