I have read and enjoyed all the previous books in the series, and this was the worst.
At over 350 pages, with a small font and narrow page margins, this book took forever to read. There are five main plot threads, including (1) a murder in Paris handled by civilian authorities, (2) an interrogation of a high level Russian defector, (3) double-agents within the US, French, and Norwegian espionage and political branches, (4) protection for aforementioned Russian defector from Russian hit squads, and (5) Scot's Horvath revenge story against his dead wife's killers.
It's all too much and well before any one thread gains traction, we teleport to another story. In the end, I didn't care about any of these stories and there was never any doubt how each would turn out. Plot twists are not part of Brad Thor's repertoire. The book reads very slowly. This book screams for an editor who can rein in the author's urge to overwrite.
As for Scot Harvath, there is no character growth. He is the same hard-charging, no-nonsense guy with barely a sense of humor as he was in book #1. The dialogue was standard for this genre (one step above grunts). the bad guys are really terrible, and none of the other characters have interesting things to say or do.
One line really irked me. I think it was the US President, speaking (I believe for the author). He complains that he doesn't understand why US citizens don't trust their government. They don't appreciate all the good things he is doing on their behalf. The entire book is about a black ops team that conducts unsanctioned assassinations around the world, with no accountability to anybody but the US President, and in gross violation of US and international law! No kidding that the public doesn't trust their government.
Read the other books in the series - they are ok. Skip this one.