Following a series of murders, an apothecary's apprentice must solve puzzles and decipher codes in pursuit of a secret that could destroy the world in this suspenseful debut novel. Christopher Rowe, apprentice to Master Apothecary Benedict Blackthorn, is learning all his master's secrets, such as how to decipher complex codes and puzzles, and how to transform simple ingredients into powerful medicines, potions, and weapons. Christopher's beloved master guides him with a firm, steady hand, a confidence even more vital as Christopher learns of a mysterious cult preying on London's apothecaries. The murders grow closer and closer to Blackthorn's shop...until Christopher is torn from his home with only a cryptic message and a warning from his master: "Tell no one what I've given you." Aided by his best friend, Tom, Christopher must race to decipher his master's message and follow a trail of deceit toward an unearthly secret with the power to tear the world apart.