Author Matthew Dunn’s background in MI6 reads like the resume of his main character, Will Cochrane, in the eponymous series of which “Act of Betrayal” is the latest. While reading all the books in the series probably gives more background to the story, this reviewer has only read the previous book, “A Soldier’s Revenge” and that gave plenty of background for this novel.

Will Cochrane is the ultimate assassin but also the ultimate friend. His actions are always based on his strict morality, which he uses to do the right thing regardless of personal cost. To save a friend or an innocent person, he would sacrifice his life. But he also is human, which  means that he’s made mistakes. In fact, he killed the wife and daughter of a Russian spy by accident after painstakingly creating a plan to kill only the spy. It backfired and killed the spy’s family instead of the spy, but that spy is now one of Cochrane’s closest allies. That doesn’t mean they go out for coffee together, but that they can rely on each other in times of great need.

And that time of great need comes into play in this story. Characters from past stories appear in this one, but unlike some writers, Dunn manages to keep the characters unique, so the different names and governmental agencies they belong to don’t get jumbled. Of course, it might also be that having read the previous book, the names were easier to keep straight, so starting at the beginning of this wonderful series of thrillers is probably the best way to read them all and get a more complete sense of who Will Cochrane really is.

In this book, Cochrane is tired of the killing and just wants to settle down with the twin sons of his good friend, another intelligence operative who was killed, and raise them to be good people. In the last book, he was prevented from fulfilling that wish. The story of the children does figure into this book, but what really comes through — and it’s a credit to Dunn’s writing chops that he can accomplish this — is Cochran’s desire to be normal, to live a normal life, and to have normal relationships.

The plot seems fairly straightforward until the twist. Three years previously, Cochrane was asked to kill a billionaire in Germany who was on his way to deliver five million dollars to a terrorist organization. Not much thought has been given to this highly secret kill until the people involved in the planning start disappearing. The reader knows they are being killed. The questions include why are they targeted after three years, and who is doing the killing?

Unwin Fox, Cochran’s CIA friend and the person who asked him to do the killing three years previously, is poisoned almost in front of Cochrane’s eyes. Cochrane, in one of the heart wrenching scenes in the story, kills him to prevent him from dying a horribly painful death. He asphyxiates his friend. That act, while merciful, causes Cochrane much anguish. And because Cochrane is such a loyal friend, he is determined to find out who killed Fox and why.

Dunn doesn’t gives clues about the twist until the reader is enmeshed in the story, and while the ending shows that Cochrane is closer to realizing his personal goal, his story is clearly not over. And that’s great news for fans of this series. Like this reviewer, they won’t want to wait to find out what happens to Cochrane’s plans to be a father and family man. And, while part of the solution to the crime as to what actually happened three years ago in Germany is revealed, there is still the question of who — in the White House — is behind the dastardly plot.

Please note: This review is based on the advanced reader’s copy provided by William Morrow, the publisher, for review purposes.