Episode 1 begins with Liz Grainger, also known as Celeste, portrayed by Buffery, as she appears to be subjected to intense interrogation by German forces. However, this ordeal is revealed to be part of her training for a clandestine organization named 'The Outfit,' which is led by Colonel James 'Cad' Cadogan, played by Glover, alongside Faith Ashley, played by Asher. The organization is actively enlisting civilians to strengthen its ranks. As the narrative unfolds, we witness Liz's training as she prepares to assume the role of an undercover agent in France, while parallel scenes introduce her fellow recruit Mathilde Firman, codenamed Aimee, played by Hamilton.
Details emerge about their pasts that led them to The Outfit. Mathilde, a London factory worker of French descent, fled to England from France with her Jewish mother early in the war. Her determination to contribute to the war effort stems from her heritage, especially after she slaps a man at a dance for calling French collaborators. Meanwhile, Liz, whose husband is away serving, has moved to Devon with her daughter Vicky following the devastation of the Blitz. Her unexpected recruitment comes after responding to a radio request for holiday photographs to aid the war effort, mirroring the real-life story of agent Odette Hallowes. Initially hesitant about undertaking such a dangerous role, especially as a mother, Liz is ultimately persuaded by Cad to undergo training, where she excels, bolstering her resolve to volunteer. Despite concerns from some members of the team regarding sending civilian women, particularly those with children, Cad champions her capabilities and endorses her as a courier.
Episode 2 shifts focus to Matty, who has returned to Stepney and the factory, while Cad laments her rejection, realizing that the pool of recruits is dwindling. He eventually calls Matty back for wireless receiving duties in England, where she bonds with fellow trainee Lois Mountjoy, portrayed by Abigail McKern. Meanwhile, Liz is in the final stage of her training, anxiously preparing for deployment alongside Colin Beale, codenamed Cyrano, played by Northam, whom Liz and Matty have grown close to during their learning phase.
As the episodes progress, the environment becomes increasingly fraught with danger. In Episode 3, Liz, Matty, and Colin arrive in Area 3 to meet alongside local communist resistance fighters under Maurice, played by Vincenzo Nicoli. Upon arrival, Liz and Matty discover a disappointing lack of security arrangements. They soon face challenges; Matty struggles with a faulty radio transmission leading to a German raid on her hiding spot.
By Episode 4, the pressure intensifies as Liz forges a connection with Claudine, portrayed by Shelagh McLeod, who lends her assistance amidst the growing threat of the Germans. Meanwhile, Matty faces her own trials—successful in her attempt to evade detection, her radio transmissions nevertheless attract unwanted attention from local German forces.
In Episode 5, the toll of espionage becomes evident on both Liz and Matty as the operation's stakes rise. Matty's frustration drives her to drastic measures, while Liz must evaporate any vestiges of her old life as the line between duty and personal grief blurs.
As we advance to Episode 6 and beyond, we witness a harrowing journey of loyalty, betrayal, and sacrifice, culminating in Matty's capture and Liz's painful choices, spurred by the ongoing conflict. The tension culminates in a desperate rescue mission and the subsequent unraveling of relationships, highlighting the stark realities of war and the personal costs paid by those working behind enemy lines.
The story continues in the unfolding of Series 2, where Liz navigates her new role in London while reflecting on her ongoing emotional connection with Kit, the complexities of new recruits, and the ramifications of past conflicts. The series takes viewers through a range of emotional arcs, showcasing the ever-evolving landscape of espionage during wartime, with relationships being tested and reinvented as the stakes continue to rise in this gripping narrative. The introduction of new characters and evolving storylines keeps the tension palpable as the war rages on, forcing the protagonists to confront their values and allegiances in a world shadowed by uncertainty and peril.