Here is a book I'd like to read, The Wives of Henry Oades, set in the 1860s in England, New Zealand, and California, and rated four stars by amazon readers. The writer, Johanna Moran, thought her fictional story was based on a historical legal fact. It was about a man who unwillingly ended up as a bigamist. The story from a legal text had been passed from her father to her mother and then to her. She worked some 9-10 years on this debut novel.
A descendant of the Oades family questioned the authenticity of the basic story. Now, facts seem to suggest that the basic events did not happen: no Maori raid and capturing of a wife, no court case against a bigamist Henry Oades, in fact no Oades in New Zealand until 1908.
Here is the long story of the unveiling of a hoax. It is the story behind the story.