Woman takes secretarial job inside Churchill's war room, to uncover a mole.

I thought of the movie "Darkest Hour"

Leaving her boring munitions factory job, avid mystery novel reader and secretary Evelyne Redfern finds herself investigating a murder in the Cabinet War Rooms and teams up with an aide to root out a mole selling government secrets.

• The first in the immersive Parisian Orphan mystery series: A Traitor in Whitehall, from bestselling author Julia Kelly.
• Evelyne Redfern isn't just the plucky and talented secretary/spy we come to know in the present day; her past as the infamous "Parisian Orphan" is
  sure to leave its mark on readers, and adds an extra layer of mystery.
• For fans of Susan Elia MacNeal's Maggie Hope series and our own Allison Montclair's Sparks & Bainbridge series.