Group Fifteen Files (Scott Mariani) Books in Order

This corner of the Group Fifteen Files universe focuses on Witness X, the novella co‑written by Scott Mariani. It keeps Mark Dawson’s covert agency framework but filters it through Mariani’s love of relentless pacing and morally tangled heroes.

The story centres on Bryan Duffy, a government agent whose career has been wrecked by a national scandal. Branded too toxic to have around, he is sent to Spain and told to sit tight until the headlines move on. Officially, Duffy is finished. Unofficially, he remains a valuable asset – the one labelled “Witness X”.

When North Korean hitmen attack a seemingly ordinary woman on a London street, the old unit calls Duffy back into service. The job sounds simple: identify the attackers, find out who ordered the hit and shut the whole thing down. Very quickly, though, he realises there is much more at stake than one target and a single operation.

As Duffy digs deeper, he uncovers a trail of secrets that runs through the British establishment and back into Group Fifteen itself. The people who burned his career may be the same ones pulling strings now. Every ally looks like a possible enemy, and each new piece of information pushes him further into a situation he may not be able to walk away from.

Mariani brings his trademark energy to the set‑pieces: close‑quarters fights, street chases and tight escapes in recognisable European locations. At the same time, the novella leaves room for Duffy’s internal struggle as he weighs duty, anger and a stubborn sense of right and wrong. He is not a clean hero, but he is trying not to become the blunt instrument others think he is.

For readers following Dawson’s Group Fifteen Files in order, Witness X slots neatly into the line‑up as one more deniable mission with its own tone and emphasis. For fans of Scott Mariani arriving from the Ben Hope books, it offers a brisk introduction to another shared world of clandestine operations, compromised officials and the occasional agent who still wants to do the decent thing.

Taken on its own terms, this mini‑series entry is a sharp, one‑sitting thriller about what happens when the person labelled a liability is the only one willing to ask dangerous questions.