Mary has a gift for languages and codes that has brought her to the attention of the adults working at Bletchley Park. She finds herself drawn into their undercover operations, learning Japanese in order to decode enemy messages - but the operation she's a part of remains cloaked in mystery. As tensions on the Home Front escalate, Mary is forced to face the realities of warfare - the enemy is operating amongst them. Posing as a waitress amidst the glamour and bustle of the Ritz Hotel, Mary uncovers secrets and lies amongst the people she's working mostly closely with. Can Mary steer clear of danger and thwart the devious mission unfolding around her? There is just one thing she knows for sure: trust no one.