This was a bit of a behemoth of a novel but worth sticking with.
Our heroine, Margaret, is trapped in shabby genteel poverty boarding house hell with her pernickerty demanding selfish widowed mother. When Margaret is let go by her employer, the bumptious Mr Plimson - who appears to only have offered her a job as he knew her father from a business partnership - things are financially impossible. Margaret is struggling to find a job until she is handed a newpaper advert for an interesting if vague opportunity.
Margaret is interviewed and turns up on her first day at a hearing trumpet shop to find its a front for an element of the Secret Service - Bureau 8. The Bureau is investigating and trying to track down and break up the terrorist group, the Scorpions, who went deep underground about 15 years before but have resurfaced with a bomb at a railway station and other similar outrages.
Margaret, initially employed as a secretary, is welcomed by this odd collection of colleagues, all men, who are vague and terribly, terribly focused, but also kind and not entirely without finer feeling.
With time short before a threatened outrage and major remassing of the Scorpions, its all hands to the pump - and this involves Margaret going undercover as the newest agent for the Bureau.
With her mother in a permenant snit, sulking and bursting into angry tears without warning or due cause, Margaret has quite enough on her plate at their boarding house - not to mention the gloomy miserable landlady, lacklustre food and concern over their future, when a new boarder, a Mr Smith, starts getting mysterious postcards in code and seemingly following Margaret about. Fired with enthusiasm, Margaret 'borrows' a postcard and unwittingly starts off on the path to solve the mystery of her father's unexplained suicide...
I do hope this is a series, because I very much enjoyed this book and genuinely took to Margaret and the odd agents of Bureau 8!