This was one of the weaker books in the Danny Black series for me. I read this kind of basic SAS operator novel for three reasons - well-organised action set pieces, an interesting variety of locations and a decent overarching plot. Nothing too complicated or metapolitical, just action with some twists and turns. This book does alright on the first, misses opportunities on the second and mostly fails on the third.
The action: the actual action scenes in the book are serviceable. There is one particularly well-structured sequence where Black ambushes an opposing SF team and one interesting infiltration of a top-floor penthouse in London. Otherwise though the action is very much your standard fare, with few really memorable encounters. Chris Ryan can be counted on to describe the action with an insider's eye but it slightly felt as if he was running out of ideas for this one.
The locations: this feels like a big missed opportunity for me. The action takes place mainly in London, Amman and Washington DC, with one additional locale I can't reveal without any spoilers. But the places are mainly interchangeable: while there is some par-for-the-course description of Amman (where I have actually lived) as sandblasted, dirty and polluted - all of which are true - most of the action takes place in a car, or in a five-star hotel in the city, so they could have been anywhere at this point. Same thing with London - there's some action in the aforementioned penthouse, a scene at MI6 headquarters in Vauxhall, and one in a warehouse in West London. Nothing to really separate it from anywhere else (Mi6 building excluded).
The plot is where the book is weakest. As other reviewers have pointed out, the story mostly continues on from previous books with the same main characters, Danny Black and Bethany White. While they are both decent characters with well-fleshed-out motivations, their struggle is more personal which moves the book away slightly from "spec ops action thriller" and more towards "personal thriller with political flavouring." Not necessarily a bad thing, but I suspect not the reason most people read these books. It also seems like the next book in the series will also mostly continue the same Bethany-Danny storyline. The main villain in the book, an almost cartoon-like Wagner Group mercenary, is also a very weak character: he likes to kill Western special forces operators, but we're never told why, or anything else about this guy at all to flesh out his character. When he is eventually dispatched it's also in almost comical Bond villain-type fashion, after smugly revealing key intelligence that drives the rest of the plot forward.
One final word on the political meta-plot of the book. While I am no fan of either Donald Trump or Vladimir Putin, the inclusion of a collusion-flavoured narrative here feels really ham-fisted and doesn't actually bring anything substantial to the table. You can see the twist in finding out who is actually behind the conspiracy (hint-it's not who you originally think is going to be the target!) unfolding in the plot from a mile away, and the sub-plot around former Guantanamo detainee Hamoud is exceedingly plodding. There is of course space for these types of plotlines, which encourage the reader to question their assumptions of who the bad guys and the good guys are, in an SAS thriller book, but it has to be done with some subtlety, lest the author leave themselves open to (not unreasonable) accusations of having "gone PC." The previous book's plotline around the rogue MI6 agent was better-constructed and more engaging in this regard.
Overall, if you're read the previous 7 books and want to keep following Danny Black's adventures you're going to have to read this one. It's not an awful book by any stretch - I still read it in a couple of days, enjoyed some of the firefights and will be back for more when Danny Black 9 is out. But it would be good to have a bit more inventive plotlines in future instalments.