Quinn Sinclair, the audacious young widow of a Union soldier, joins forces with an unvarnished ex-Confederate POW named Garnick to form a detective agency in 1867 Chicago. The detectives take on two cases on the same day - one to help a man prove he didn't kill his wife, the other to help a lawyer find reasonable doubt that his client killed her ex-lover's new bride. As the investigation proceeds, they discover facts that tie the cases together in disturbing ways. Quinn, who uses the name Mrs. Paschal professionally, is determined to prove their client innocent. But in 19th Century Chicago, innocence is a matter of degree. A sensational arson and murder, a yellow press, corrupt politicians and a bevy of colorful bawdyhouse madams make seeking justice a dangerous business. Not least among Quinn's worries, somebody seems intent on murdering her!