The Lighthouse is a 2005 detective novel by English writer P. D. James, the thirteenth book in the Adam Dalgliesh mystery series.

Adam Dalgliesh is brought in to investigate the mysterious death of a famous writer on a remote and inaccessible island off the Cornish coast.

Combe Island is a discreet retreat operated by a private trust, where the rich and powerful find peace and quiet.

Dalgliesh recovers from his illness, and after the break of the investigation and quarantine, he and his lover Emma both overcome their fears about each other's seeming lack of commitment, and agree to marry.

"[1] Kirkus Reviews wrote: "Although the story is briefer than James’s recent double-deckers (The Murder Room, 2003, etc.