Dark Places by Gillian Flynn (2009)

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Another dark, gothic novel by Flynn about a woman who was the sole survivor of the massacre of her family in 1985. Her brother went to jail for the crime, amidst claims of Satan worshipping, but as the money from the her memorial fund runs out, she hooks up with a "kill club" who try to solve mysteries. Told in alternating chapters from the present day and the past, and through alternating viewpoints. Flynn has an amazing gift for description, for suspenseful writing and clever turn of phrase.  See also Sharp Objects and Gone Girl by Flynn.