In the novel Hallowe'en Party, Sandra Griffin is married to Harry, the landlord of The Green Swan pub at Woodleigh Common. She had an affair with Lesley Ferrier. When Lesley was found murdered near the pub, stabbed in the back, both Sandra and her husband became suspects although nothing was ever proven.
According to Superintendent Spence, Lesley was said to have broken up with Sandra and gone for another girl or several other girls. According to Jeremy Fullerton, a solicitor and Lesley's former employer, this break up had led to a violent row at the pub. Lesley was then stabbed on the way home. There was a lack of firm evidence and any definite facts and the public prosecutor threw out the case against Sandra. However, when asked to speculate, Fullerton told Poirot that "Hell hath no fury like a woman scorned." It is something he says is always being quoted in court and sometimes true.
According to Superintendent Spence, Sandra was, and still is, handsome, although she might be getting "a bit long in the tooth". She is "half gypsy" and is described as being "a temperamental piece".