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--like 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.