Anne Beddingfeld holds the clue to a mystery. With the strange scrap of paper she discovered she can forge a link between a diamond robbery, an accidental death, a London tube station - and a murder in a remote country mansion! Anne's journey to unravel the mystery takes her as far afield as Africa and the tension mounts with every step...

First published in 1924 the novel was adapted for television by CBS in 1989, and featured Edward Woodward, Tony Randall, Rue McClanahan and Ken Howard in major roles. The film updated the setting and characters to a contemporary period.

Christie introduced Secret Service agent Colonel Race in this novel and he appeared in three further novels: Cards on the Table, Death on the Nile and Sparkling Cyanide. The money that Christie received for the serial rights from The Evening News paid for her first car - a Morris Cowley.