Osla meets Prince Philip at a New Year's Eve dance, connecting over a shared kiss after dancing in her factory clothes.

Mab and Osla meet on a train, discover they share a destination, and arrive at Bletchley Park together.

Beth is hired at Bletchley Park in an interview and assigned to Dilly Knox's all-female codebreaking team.

Dilly's team decrypts Italian battle plans, contributing directly to a decisive Allied naval victory at Cape Matapan.

Winston Churchill tours Bletchley Park, hears Mab demonstrate the bombe machines, and gives an inspiring speech to the workers.

Francis proposes to Mab impulsively after she defends the morale-boosting importance of stylish hats.

Dilly's team breaks a critical German Enigma code on the same day the United States enters the war.

Mab and Francis marry impulsively the day after reuniting, before he must leave on another assignment.

An air raid over Coventry kills Lucy and Francis when a bombed structure collapses on them.

Mab blames Osla for Lucy's death at Francis's funeral and tells her never to speak to her again.

Beth cracks Dilly's unsolved Rose Code and discovers encrypted evidence pointing to a traitor inside Bletchley Park.

Two men arrest Beth, sedate her, and deliver her to Clockwell Sanitarium on Giles Talbot's orders.

Beth smuggles coded messages out of Clockwell Sanitarium to Mab and Osla, alerting them that she was framed.

Mab and Osla visit Beth at Clockwell, hear her account of Giles's betrayal, and help her escape.

Giles is tackled at a train station during the royal wedding broadcast, arrested, and later convicted of treason.

Three women — socialite Osla, ambitious Mab, and reclusive Beth — are each assigned to Bletchley Park's top-secret codebreaking operation as World War II begins. Their work yields critical military victories, but the war also brings devastating personal losses, especially when a Coventry air raid kills two of Mab's loved ones and fractures the women's friendship. Years later, Beth smuggles messages from inside a psychiatric hospital, alerting Mab and Osla that a colleague framed her to cover up his wartime treason. The estranged women reunite, help Beth escape, and race to crack the final evidence needed to expose the traitor. Their pursuit ends in a chaotic arrest at a train station, but the truth ultimately wins out. Beth is cleared, their friendship is restored, and they make one final visit to the place that defined them.

The headline events that drive the story from wartime Bletchley to postwar justice.

Osla drills metal sheets at an airplane factory alongside her friend Sally before being transferred to Bletchley Park.

Mab launches the Mad Hatters Tea Party book club, inviting colleagues from Bletchley Park and bringing Beth along.

Mrs. Finch scolds Beth for attending the pub meeting, pinches her arm, and forces her to hold up the family Bible.

Beth tells Mab the German invasion of England was postponed, immediately regretting the violation of the Official Secrets Act.

The Café de Paris is bombed while Osla is inside; a mysterious stranger wraps her in his coat and helps her escape.

Mab is reassigned from Hut 6 to operate the large, clattering bombe machines in Hut 11.

Beth picks up a stray schnauzer named Boots on her way home after a successful codebreaking shift.

Lord Mountbatten makes an unannounced visit to Bletchley Park, and Osla thinks she sees someone slipping out of her hut.

Commander Travis interrogates Osla over suspected information leaks to Prince Philip and orders her to stop writing to him.

Harry tells Beth he has convinced Commander Travis to let him enlist in the naval air service, ignoring her pleas to stay.

Mab and Osla admit to Commander Travis during his investigation that Beth once violated the Official Secrets Act.

Osla translates a series of increasingly panicked German messages as the Allied invasion of France unfolds.

Mab accepts a transfer to London, and she and Osla part company on cold, unfriendly terms.

Giles visits Beth in Clockwell and threatens to arrange a lobotomy unless she reveals where she hid the Rose Code documents.

Major John Cornwell arrives at the jail after Giles's capture; Osla kisses him through the bars and calls Prince Philip's private line.

Before reaching Bletchley Park, Osla spends time doing factory work, and each woman navigates the social expectations placed on her before the war upends everything. Life at Bletchley brings its own pressures — noisy bombe machines, security interrogations, and the strain of keeping secrets from everyone outside the gates. The war's violence intrudes directly when Osla is caught in a London bombing and later when Harry enlists despite the danger it poses to both his safety and Bletchley's secrecy. Back at headquarters, Giles quietly maneuvers against those who might expose him, including engineering Osla's interrogation and ultimately threatening Beth with a lobotomy inside Clockwell. The postwar effort to free Beth and stop Giles depends on help from unexpected allies, including a long-lost stranger whose coat Osla never returned. The resolution arrives only after Osla makes a well-timed phone call to a prince on his wedding morning.

The significant scenes and pressures surrounding the women's wartime lives and postwar reckoning.

Osla requests and is granted a transfer from secretarial duties to a translation position at Bletchley Park.

Beth makes her first major cryptanalysis breakthrough, earning Dilly Knox's highest praise and an invitation to breakfast at his home.

Mab meets Francis Gray after his car nearly hits her on a walk, and she accidentally insults his war poetry.

Mab and Francis spend their honeymoon in the Lake District, where each opens up about the trauma they carry from their pasts.

Sheila Zarb invites Beth for a drink and explains that she and Harry share an open marriage, leaving Harry free to pursue others.

Mrs. Finch throws Boots out of the house, prompting Beth to recover the dog and confront her mother about her right to independence.

Beth and Harry spend a Sunday afternoon in Cambridge, ending with them having sex in the back of his old music shop.

Beth decodes a message warning that Coventry is a bombing target but decides not to alert Mab and Osla, keeping the secret.

Beth visits the dying Dilly Knox, who describes his unsolved cipher as resembling a rose with overlapping petals spiraling to its core.

Osla accepts Giles's marriage proposal despite not loving him, shortly after learning that Philip sparked a romance with Princess Elizabeth.

Mab and Osla meet at a teashop in York, still estranged, and after trading barbs, reluctantly agree to visit Beth together.

Mab realizes during Beth's explanation that Giles used her drunken state to steal her filing keys and access classified Bletchley documents.

Harry brings Boots to Beth at the warehouse; they reunite, spend the night together, and return to cracking the final Rose Code messages.

Osla meets Prince Philip privately at the palace, and he tells her she proved herself far more than a silly socialite.

Beth, Mab, and Osla make a final visit to a silent Bletchley Park and quote Dilly's poem to each other as they part.

Each of the three women undergoes a series of quiet but decisive turning points that shape who she becomes by the novel's end. Beth transforms from a repressed, self-doubting daughter into a confident codebreaker through key breakthroughs and hard-won personal choices, including a secret affair with a married colleague and a defining refusal to compromise Bletchley's security even for the people she loves. Mab gradually dismantles the walls built around her by trauma, learning to trust Francis and, much later, her second husband — a process that begins with small moments of honesty and ends with the courage to grieve openly. Osla moves from performing the role of a silly socialite to claiming her own worth, a journey confirmed when Prince Philip acknowledges what she sacrificed. In the postwar timeline, revelations about Giles's manipulation emerge piece by piece until the full picture snaps into place, allowing the women to act. Their final reunion at Bletchley Park — quoting Dilly's poem to each other — signals that the changes wrought by the war are permanent and, ultimately, their own.