Hagar — Barbara Hambly

A novelette of 13,000 words in the Benjamin January Free Man of Color historical mystery series. Benjamin is out of town again, and his wife Rose attends a party with her obnoxious mother-in-law, at a plantation owned by a free colored relative. When the white mistress of the neighboring plantation is murdered, and the house burned, it seems obvious that one of the household slaves committed the crime - but Rose seeks to prove differently.