L'investigatore olistico Dirk Gently

Dirk Gently's Holistic Detective Agency is a humorous detective novel by English writer Douglas Adams, first published in 1987. It is described by the author on its cover as a "thumping good detective-ghost-horror-who dunnit-time travel-romantic-musical-comedy-epic".

The book was followed by a sequel, The Long Dark Tea-Time of the Soul. The only recurring major characters are the eponymous Dirk Gently, his secretary Janice Pearce and Sergeant Gilks. Adams also began work on another novel, The Salmon of Doubt, with the intention of publishing it as the third book in the series, but died before completing it.