Charlotte Parker, a quiet American biochemist, is trying to live out a humdrum life in post-war, near-future London. After an unexpected transfer to a new position at her laboratory, she is drawn into a circle of friendship with her new coworkers and finds herself entangled in an illicit organization where she is unable to tell friend from foe. What's more – a new and forbidden love interest is pulling her deeper into the fold. Charlotte must choose to continue her under-the-radar lifestyle or risk it all for an organization that may be playing her for a fool.