When reclusive artist Gabriel Quinn is gunned down outside a gallery on Oxford High Street, Detective Inspector Bridget Hart investigates the world of contemporary art, where paintings can change hands for millions in the auction room.

Bridget is convinced that the last words spoken by the artist – a mysterious code of 8 digits and a letter – are key to unravelling the mystery of his death.

But when her ex-husband, Ben, now a senior detective with the Metropolitan Police in London shows up with new information about the murdered man, Bridget's personal and professional lives are brought crashing together with dramatic consequences.