Anthony is a successful British author and screenwriter who finds himself reluctantly pulled into a real-life murder investigation. Acting as a semi-fictionalized narrator, he chronicles the unfolding case while attempting to impose the structured logic of classic detective fiction onto chaotic real-world events. He relies on his professional writer's instinct, though his analytical approach often clashes with the unpredictable nature of actual police work.

Hawthorne is an enigmatic, abrasive former police detective who operates as a private investigator. He possesses near-superhuman observational skills in the vein of classic literary sleuths, allowing him to quickly identify the hidden shape of complex crimes. Deeply private about his past and his abrupt dismissal from Scotland Yard, his unconventional methods frequently alienate suspects and colleagues alike.

Richard is a wealthy Hampstead divorce lawyer known professionally as "the Blunt Razor" due to his formidable legal reputation. Despite his strict teetotaler lifestyle, he is found bludgeoned to death in his home with an expensive bottle of vintage wine. His scrupulous public persona hides a complex personal life, including a history of providing quiet financial support to the family of a deceased university friend.

Davina is an interior decorator and the widow of Charles, who died in a tragic caving accident years earlier. She maintains a close, platonic bond with Richard Pryce, who serves as a surrogate father to her teenage son. She is surprised to learn that she is the recipient of a significant financial bequest in Richard's will.

Colin is Davina's fifteen-year-old son, who lost his father in a cave flooding incident. He is deeply influenced by his reading habits, holding a particular fascination with Sherlock Holmes mysteries. He maintains a strong attachment to his godfather, Richard, whom he views as a secondary father figure.

Akira is a celebrated literary author and intellectual known for her poetry and feminist critique. She recently went through an acrimonious divorce settlement overseen by Richard Pryce. A highly publicized incident where she poured wine over Richard and threatened him makes her a primary person of interest in the investigation.

Adrian is a wealthy individual who recently endured a contentious divorce from Akira Anno. He originally gifted the expensive bottle of wine that was later used to murder Richard Pryce, presenting it as a thank-you for the lawyer's representation. He harbors deep resentment toward his ex-wife and attempts to direct the investigators' attention toward her.

Gregory is an old university friend of Richard Pryce who suffers from a severe connective tissue disorder. Facing a terminal diagnosis, he travels from Yorkshire to London to ask his wealthy friend for financial assistance with a medical operation. His sudden death at King's Cross station introduces a parallel layer of complexity to the investigation.

Cara is the lead Detective Inspector assigned to investigate Richard Pryce's murder. Territorial and aggressive, she deeply resents Hawthorne's interference in her jurisdiction. She regularly employs intimidation tactics, pushing Anthony to act as a covert informant against his investigative partner.

Stephen is Richard's grieving husband and the primary heir to his estate. He claims to have been returning from their secondary home at the time of the murder, though physical inconsistencies with his vehicle immediately raise the investigators' suspicions regarding his timeline.

Susan is Gregory's widow. She provides crucial background information regarding her husband's deteriorating health, his financial desperation, and his final voicemail expressing joy over a successful meeting in London.

Oliver is a law partner at Masefield Pryce Turnbull and the executor of Richard's will. He maintains a cooperative but careful demeanor, shedding light on his late colleague's recent ethical concerns regarding a client's financial disclosures.

Dawn is a publishing professional who works closely with Akira Anno. She inserts herself into the investigation by providing an alibi for her high-profile client, demonstrating a fierce loyalty to the author's public reputation.

Kevin is a young man with muscular dystrophy who lives in the same building as Hawthorne. He possesses strong technical skills and shares a quiet, friendly understanding with the otherwise unapproachable detective.

Darren is a Detective Constable who works directly under Cara Grunshaw. He acts as her enforcer, physically intimidating witnesses and assisting in her ethically questionable tactics against Anthony.

Jill is Anthony's real-life wife and the producer of his television series. She focuses on maintaining the filming schedule amidst numerous setbacks and expresses clear frustration over her husband's dangerous extracurricular activities.

Lofty is a former police officer who transitioned into working as an asset trader. He operates with a deep distrust of his former colleagues and is connected to the victim through a private financial investigation.

Dave is an experienced cave rescuer based in the Yorkshire Dales. He possesses intimate knowledge of the local underground systems and shares his lingering unease regarding a fatal accident he responded to years ago.

Hilda is Anthony's literary agent. She provides a grounded, industry-savvy perspective, helping him draw connections between various figures operating within London's publishing circles.

Henry is a neighbor living near Richard Pryce's modernist home in Hampstead. He provides a critical piece of the timeline by reporting a figure approaching the victim's house shortly before the estimated time of death.

Faraz is an assistant who works closely with Stephen Spencer. He is present with his employer on the night of the murder, providing an alibi that Hawthorne immediately scrutinizes.

Lisa is a neighbor of Daniel Hawthorne and the mother of Kevin. She hosts the local literary discussion group that Hawthorne occasionally attends.