Third Girl

S11 E3: Celebrated Belgian detective Hercule Poirot is joined by crime novelist Ariadne Oliver (Zoë Wanamaker – My Family; Harry Potter) as he attempts to prove the innocence of a Norma Restarick (Jemima Rooper – Lost In Austen), a young girl accused of murder. The mystery stretches back 18 years to the suicide of Norma's mother, but as the plot unravels, Poirot discovers that the solution hinges on a shocking revelation. Also starring Peter Bowles (To The Manor Born), James Wilby (Gosford Park) and Haydn Gwynne (Rome).