The author of the Richard Sharpe series of historical novels tries something new: a whodunit set in 1820s London and featuring Rider Sandman, a cricket-playing gentleman soldier who’s just returned from Waterloo. A hero but guinea-less, Sandman accepts a commission from the Home Secretary to confirm the guilt of a young painter convicted of raping and murdering a countess. Though innocent, the poor lad has got an appointment with the hangman in one week’s time. The quick-tempered Sandman leaps, rides, and slashes his sword to the rescue, joined by colorful cohorts straight out of Masterpiece Theatre central casting — there’s a reformed rogue, a bookish fop, a spunky virginal lady, and a saucy tart. Cornwell convincingly captures the sights, slang, and even smells of Regency England, a time when a child could be executed for a petty crime.