Morgan Capell's life is falling apart by small degrees — his father's dead, his boyfriend dumped him, and his mother's in the grip of dementia. His state of mind isn't helped by his all-too-real recurring nightmare of the wreck of the Troilus, a two-hundred-year-old ship he's been dreaming about since his teenage years.

The story of the Troilus is interwoven with the Capell family history. When amateur historian Dominic Watson inveigles himself into seeing the ship's timbers which make up part of Morgan's home, they form a tentative but prickly friendship that keeps threatening to spark into something more romantic.

Unexpectedly, Dominic discovers that one of the Troilus's midshipman was rescued but subsequently might have been murdered, and persuades Morgan to help him establish the truth. But the more they dig, the more vivid Morgan's nightmares become, until he's convinced he's showing the first signs of dementia. It takes as much patience as Dominic possesses — and a fortuitous discovery in a loft — to bring light out of the darkness.