The Mystery of Three Quarters

Author	Sophie Hannah
Language	English
Series	Hercule Poirot
Genre	Detective, mystery
Published	August 23, 2018 HarperCollins
Publication place	United Kingdom
Media type	Print (hardback and paperback)
Pages	400 pp (first edition, hardcover)
ISBN	978-0008264451
Preceded by	Closed Casket
Followed by	The Killings at Kingfisher Hill

The Mystery of Three Quarters^[1][2] is a work of detective fiction by Sophie Hannah. It is the third in her series of Hercule Poirot novels, after being authorised by the estate of Agatha Christie to write new stories for the character. The previous two are The Monogram Murders (2014) and Closed Casket (2016).

Four people receive letters purporting to be from Hercule Poirot and accusing them each of the murder of Barnabas Pandy, a ninety-something businessman who drowned - accidentally, it seems - in his bath. Poirot has no knowledge of the letters, nor yet of the late Barnabas Pandy, until he is accosted by one of the recipients, society woman Sylvia Rule, before finding another, market trader John McCrodden, in his drawing room. As he begins to investigate the source of the letters with assistance from his young friend Edward Catchpool, a Scotland Yard detective, he comes into contact with the family of Pandy, which seems to be hiding secrets.

Poirot refers to the case as "the mystery of three quarters" because, of the four people who received letters purporting to be from him, three are in some way connected to the late Barnabas Pandy, whose murder the letters accuse each one of. The fourth, however, is seemingly unconnected. Poirot, then, must figure out the relevance of the fourth person, or quarter. To symbolise the four quarters Poirot uses a slice of Church Window Cake, whose fourth square is separated from the other three.

• Hercule Poirot, private detective
• Edward Catchpool, inspector from Scotland Yard

• Hugo Dockerill, housemaster to Pandy's great-grandson
• John McCrodden, seemingly unconnected to Pandy
• Sylvia Rule, mother of a boy in the same school house as Pandy's great-grandson
• Annabel Treadway, Barnabas Pandy's granddaughter

• Kingsbury, Pandy's butler and closest friend
• Ivy Lavington, Treadway's niece
• Lenore Lavington, Ivy's mother
• Timothy Lavington, Lenore's son
• Rowland "Rope" McCrodden, John's father, a solicitor nicknamed "Rowland Rope" due to his preference for capital punishment
• Freddy Rule, Sylvia's son and Timothy's classmate
• Mildred Rule, Sylvia's daughter

• The Mystery of Three Quarters on the official Sophie Hannah website
• The Mystery of Three Quarters on the official Agatha Christie website