Olivia Williams

Character: Agatha Christie

Anna Massey

Character: Old Agatha Christie

Raymond Coulthard

Character: Archie Christie

Stephen Boxer

Character: Psychatrist

Anthony O'Donnell

Character: Hercule Poirot

Anthony O'Donnell

Character: Kenward

Mark Gatiss

Character: Kenyon

Richard Leaf

Character: Gunman

Bonnie Wright

Character: Young Agatha Christie

Celia Montague

Character: Agatha Christie's Mother

James Tucker

Character: Reggie

Vicki Pepperdine

Character: Carlo Fisher

Bertie Carvel

Character: Max Mallowan

Edmund Kingsley

Character: Soldier

Gregory Finnegan

Character: Band Member

Toby Stephens

Character: Doctor Edward Armstrong

Agatha Christie

Character: Self (archive footage)