"When Calla Cress, a skilled government agent, and codebreaker, begins to unravel the secrets of the legendary Beale Ciphers, she finds herself framed for the murder of her closest friend. On the run and discredited, Calla embarks on a treacherous journey to Africa, where she discovers that a vengeful enemy is out for blood and plans to use the Beale Ciphers to unleash hell on Earth."