Composer Geoffrey Vintner heeds a call from Gervase Fen summoning him to the small cathedral city of Tolnbridge, which was once a hotbed of devil-worship. The cathedral's organist has been attacked, and Geoffrey is the replacement… but someone doesn't want him taking the post. Geoffrey overcomes these assaults and makes it to Tolnbridge, and Gervase Fen, who is working "together" with spy-hunting Inspector Garratt. But before Fen is able to check his theories, he and Geoffrey become ear-witnesses to an impossible death in the…