The Small Back Room – Nigel Balchin

This was one of those random purchases from a charity shop that turned out to be an absolute zinger.

It opens with an apparently humdrum depiction of a Whitehall department during WWII. We follow one man through a series of meetings, various discussions of engineering geekery and an unsatisfactory relationship. Gradually, the importance of these bureaucratic shenanigans to the broader war effort becomes clear, and an outbreak of deadly mines brings our hero to a moral and personal breaking point.

The writing is unflashy and smart, the characters all convince and the plotting ingenious.