A Spell of Vengeance — D.B. Jackson

Ethan Kaille is a thieftaker in Colonial Boston, scratching out a living by restoring stolen property to its rightful owners. But unlike others in his profession, Ethan relies on magical spells as well as his wits to track down thieves. Being a conjurer doesn't make him popular with the law in Boston, so Ethan is taken aback when the sheriff seeks his help in settling a dispute between a pair of wealthy merchants and a ship's captain who has threatened their lives. Ethan knows the captain can back up his threats with magic of his own. But there is more to this matter than the merchants have let on, and Ethan soon discovers that what he doesn't know might actually kill him.