The second in his trilogy, called First Dig Two Graves, is set in and around Shrewsbury, Iran, and London, and although a standalone novel, he says it follows on from the first book, with many of the same characters.
It revolves around an agent of the Iranian secret service who blames a naive gravedigger called Justin Parkes for thwarting his terror plot, and vows to take a terrible revenge.
Meanwhile the first book in the series, called A Very Deadly Sin, has been rewritten and re-edited to produce a revamped second edition.
Both thrillers are available on Amazon as e-books or paperbacks.
Shrewsbury-born Denis' life story is nothing if not varied. As a young man he served in the army as a vehicle mechanic, and later signed up as a Sergeant in the Rhodesian Army.
"Later I worked as a driver/bearer for a firm of undertakers – and yes, I did manage to drop a corpse in the street. This was followed by a two year spell as a self-employed gravedigger."
After a brief and unhappy time working for HM Customs and Excise he had an enjoyable six years as an assistant air traffic controller at RAF Shawbury, followed by a year as manager of the e-learning centre at Tern Hill barracks.
In a complete change of direction he trained as a reflexologist and practised for many years in Market Drayton.
Denis says: "But my humdrum life was not yet over. Needing a change and with my versatility knowing no bounds, for several years I worked as a volunteer for a political party, and eventually was employed as a political adviser for an MEP. Finally, for two years before my well-deserved retirement, I served as a detention officer with West Mercia Police at their custody suite in Shrewsbury.
"After retirement I started to write a thriller trilogy. Unsurprisingly, I’ve woven my life and work experiences into the first completed book."