The Little Murders of Agatha Christie

Taken at the Flood (1x8)

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When a popular young girl marries a millionaire who could be her grandfather, and the bad tongues go wild. But when he dies in an arson attack and the family discovers a will in favor of the young widow, the police get involved. The whole family relied on the inheritance and stands as one man against the young woman and against her brother, a disturbing adventurer. Who is the girl really? A white goose or an unscrupulous manipulator?