Third Girl

A young woman turns up at Poirot's flat, says she may have committed a murder, and leaves when she sees how old he is. Ariadne Oliver tracks her down: Norma Restarick, who shares a London flat with two other girls. Norma hates her stepmother, dates a long-haired young man and lives in a fog, with memory gaps. Her father has just come home from Africa after 20 years away. A neighbor in her building is found dead. Poirot discovers Norma was being drugged on purpose so she'd believe she was a killer. The man claiming to be her father is an impostor, and her flatmate Frances Cary, his accomplice, also posed as the stepmother.

1. Behind the scenesPoirot in swinging London

   At 75, Christie drops Poirot into 1960s London, with long-haired kids, drugs and shared flats.

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2. ChangeBack to the 1930s

   The 2008 ITV episode pulls the story out of the 1960s into the 1930s, like the rest of the series, swapping hippies for society youth.

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