Oliver is surprised to discover that the minister of the church is an old school friend, the Reverend Paul Piltdown. Piltdown soon confides to them that the recent arrival in the congregation of lay preacher Nigel Tapster, whose influence over the young people threatens to create a separate cult, has the church members up in arms.
Wondering if Tapster is a better subject for his article, Oliver visits the lay preacher later that week, only to discover that Tapster was surprisingly voted onto the diaconate of the church, replacing long-serving deacon Cedric Potiphar at the day's previous meeting.
But the following Sunday, as communion wine is passed out, Tapster takes a drink, falls convulsing to the floor, and dies. Having passed the glass to Tapster, Piltdown becomes the main suspect in his poisoning. Both Oliver and his new girlfriend, Detective Sergeant Effie Strongitharm, strongly feel that Piltdown has been wrongly accused, and that they must find out who in the congregation had the best motive for revenge.




