《The Ministry of Unladylike Activity》系列第三集,延續二戰背景,由被稱「兒童文學界的Agatha Christie」的Robin Stevens為各位讀者帶來更多刺激的謎團探索。故事設定在1941年12月,接近聖誕節時,一顆炸彈轟炸了Deepdean女子學校,混亂中May和Nuala被送往May的姐姐Hazel Wong所在的布萊切利公園(Bletchley Park)——英國著名的密碼破解中心。抵達後,她們立刻陷入迄今最危險的案件:一名破譯員遭槍擊,表面看似意外死亡,卻在口袋中發現一則可疑且極機密的訊息。這名破譯員究竟是為敵方工作的間諜?還是有人栽贓陷害?更令人吃驚的是,Daisy的哥哥Bertie Wells成了嫌疑犯。May、Nuala和朋友Eric必須揭開真相,證明Bertie的清白。但身處充滿英國最聰明頭腦的神祕布萊切利公園,他們必須小心觀察、仔細聆聽,破解層層謎團,並揭露令人震驚的幕後秘密。'Robin Stevens is Agatha Christie for children' - Katherine Rundell‘It’s hard to know where to start. There’s so much to say – about the murders, and the codes, and the spy, that I’m getting tangled up in the story already...'It's December 1941, and almost Christmas, when a bomb falls on Deepdean School for Girls. May and Nuala are whisked away from the chaos and sent to stay with May's big sister, Hazel Wong, who is working at Bletchley Park.Within seconds, they're thrown straight into their most dangerous case yet. A codebreaker has been shot in what appears to be a