During The Blitz in wartime London, an actor suffers concussion and believes himself to be the character he has most recently been playing - a vicious strangler with a hit list of potential victims.
This film has been championed since 2013 by the British movie podcast "AttaboyClarence", (named after the final line in It's A Wonderful Life) in which the Strangler's reading of the word "Canterbury..." has become the podcast's catchphrase.
