The Assassin's Curse

After surviving multiple deadly adventures, young apothecary Christopher Rowe thinks he might finally get a break when invited to meet King Charles. Instead, an assassination attempt leaves him with only a cryptic coded message as a clue, warning that more attacks are coming. His code-breaking skills lead Christopher and his friends to Paris, where they must unravel a centuries-old curse threatening the French throne and uncover an ancient treasure before the next strike. Book three in the Blackthorn Key series.