Anton Lesser reads JB Priestley's atmospheric war-time thriller, set in a Midlands town during the blackout.

Sensitive information is being leaked to the enemy, and the department of counter espionage has sent in Humphrey Neyland to try and discover who is responsible. As the tangle of information he has collected gets increasingly complex, Neyland enlists the help of a local policeman, the experienced Superintendent Hamp.

Abridged and produced by Jane Marshall Productions for BBC Radio 4. Show less