Between two and three.
This book starts out well. Liam's infatuation with Rachel was introduced in the last book of the series: Hot Zone. They're good characters with interesting backgrounds. Dogs are involved, so that's always a plus.
The problem is with the story. The setup is great. I was all in. By half-way through I felt like we were in a rut with padded inner monologues and little progress on contrived obstacles.
Romantic suspense often has a frustrating section like this. From about 50% to 75% we're just bogged down. (No pun intended if you've read the book) And the secondary romance didn't help matters. This was a couple that could have used their own book, but were given a substantial amount of time in this one. It undercut Liam and Rachel's story quite a bit while leaving that featured story line somewhat dissatisfying.
And then, what happens around 76% is so absurd, so unintentionally hilarious, the entire book can't be taken seriously. Which is fine, I suppose, because the mission itself becomes vague and ill defined after that.
I wanted more for these characters because I think their chemistry worked and they had a potentially interesting future in front of them. That issue was dropped completely in favor of just doing the same thing as before and hoping for different results.
I like Catherine Mann and I think she's above average as an author of RS. This is the third in Mann's "Elite Force" series and I did really like the first two. I will read the next one because I like the characters, but if it goes off the rails as this one did, I may drop the whole thing.