This is another time travel, multiple universe novel. That is not a criticism merely an observation. This story introduces the Closer's a multiverse villain and the Athenians a counter balancing time space police force. Mark Strang is introduced as a professional bodyguard who acquires a very personal reason for a vendetta.
Home grown terrorists are the lead in of the story. Mark Strang is the thread that weaves through the story. The story leads through parallel universes and ends up with a world where Hitler won WWII. There is even a young protégé in the wings of the name Porter. Porter is important to multiple universes. I smell the influence of the Terminator series. In all fairness there are so many time traveler, multiverse, parallel world books that it would be pretty difficult not to see so similarities between plots. That does not denigrate this book.
The plot was reasonably complex, the action was robust and interesting. I always enjoy the named personalities and their alter egos in the alternate universes. Patton in this book, appeared to be much more likeable than he was in our universe.
I liked the book and hope to read further in the series.
This book may have been received free of charge from a publisher or a publicist. That will NEVER have a bearing on my recommendations.