SANDS, Kevin. The Blackthorn Key. 384p. ebook available. S. & S./Aladdin. Sept. 2015. Tr $17.99. ISBN 9781481446518. LC 2014048032. Gr 4-6–An auspicious debut middle grade novel. Set in the 1600s, the story revolves around Christopher Rowe, the apprentice to a Master Apothecary. After losing his master, Christopher begins to unravel a series of complex codes that his master had, unbeknownst to Chris, been preparing him to solve all along. The more that the protagonist uncovers, the more he finds himself in danger, along with his loyal-to-a-fault best friend. The story is well paced, managing not only to keep readers hooked but also second guessing everything they think they know. Sands integrates a series of fun and interesting riddles and codes with chemistry concepts—no easy feat. The ending is dynamic and rewarding, with just the right blend of the fantastical and realistic. One of the true triumphs is the author’s ability to create a character who feels accurate for the time period, while also displaying a modern sensibility that will keep readers engaged. The action does get intense but would still be appropriate for upper elementary school students.