Flashman and the Angel of the Lord finds Flashy back in America where everybody wants him to be the aide-de-camp to the abolitionist John Brown, who’s plotting a raid on the federal armory at Harpers Ferry. The Underground Railroad want him to help Brown to start a slave rebellion; Kuklos (a proto KKK) want Brown to start a civil war to cause disunion; and finally the secret service want Flashman to sabotage Brown so as to avoid a civil war. Flashman is left with no choice but to spend a few months undercover with Brown with a Kuklos spy at his side to keep him from running. The raid is unsuccessful, Brown is tried for treason, becomes a martyr for abolition in the dock, and is executed.
Fraser points his keen historical gaze towards the leadup to the Civil War and paints a half-admiring portrait of John Brown. Entertaining but not one of the better Flashman novels.