A detective mystery book set in London during the early 20th century.

After beginning work as Michael Marks's secretary, Kimbrel soon finds himself entangled in a puzzling disappearance. Known for his modern innovations and bachelor lifestyle, Marks mysteriously fails to appear in his home, despite evidence suggesting he returned the previous night. Kimbrel, along with Marks's niece Peggie Marvell and the eccentric Mr. Tertius, begins an investigation that rapidly takes a dark turn when Marks's body is discovered at his estate office, leading to an investigation that peels back layers of secrecy and betrayal.

Kimbrel’s world is thrown into disarray when he receives a frantic call from Marks's butler claiming Marks is missing. Despite initial suggestions that Marks might have stayed elsewhere, Kimbrel discovers that Marks did come home but vanished mysteriously. As Kimbrel, Peggie, and Mr. Tertius grapple with the unsettling situation, the narrative reveals numerous complications and mysterious behaviors that paint a complex portrait of Marks's private and professional life.

Marks's death is shrouded in perplexing elements: found dead in his private office with a revolver nearby, initial observations suggest either suicide or murder. Peggie and Kimbrel explore the possibilities, rejecting the notion of suicide and leaning towards murder. Marks’s nephew Barthorpe, who arrives and reveals a striking resemblance to the deceased, quickly takes charge, coordinating with police officers while excluding Mr. Tertius from their inquiries, which raises further suspicion. Tensions run high as various characters’ loyalties and intentions come under scrutiny.

The investigation uncovers a web of deceit involving significant sums of money, business dealings, and strained family relationships. Barthorpe and Kimbrel discover various clues pointing towards possible suspects, including Marks's routine manipulation and Mr. Tertius's peculiar behavior. Interactions with the police reveal inconsistencies and complications surrounding the timing of Marks's death, leading to growing confusion about who could have had the means and motive to kill him.

As Kimbrel and Peggie piece together the mystery, they encounter several secondary characters who add layers to the narrative. Among them is Frank Burchill, a former secretary to Marks, whose actions and knowledge of Marks's dealings add intrigue. A critical element emerges when characters discover Marks had been handling large amounts of money and valuable jewels, linking his death to potential theft. Key figures become embroiled in escalating tensions as motives reveal themselves.

Burchill, now functioning as a rogue detective, tracks Marks's movements the night of his murder and highlights the role of a mysterious 'Mr. X.’ This climaxes in Burchill confronting the true culprit in a dramatic revelation, asserting that James Frankton, Marks's office manager, is guilty. Burchill's accusations are concurrent with police findings, leading to Frankton's confession under Benson’s interrogation.

The resolution sees justice rendered as Frankton's arrest unravels the case's complexities, implicating Barthorpe and Burchill in their schemes to alter Marks's will. Their intentions to invalidate the current will for personal gain fail as Peggie and Kimbrel reflect on the consequences and truths unearthed regarding Marks's demise.