There was a point early in the book where I wasn't sure if I was going to have to DNF or not. It was so slow to get going and way too overly detailed on yacht piloting and such.
Once the action picked up a bit, it got a lot better.
Emma is a former CIA agent hired by St Kilda Consulting (this is the 5th in the series and the first I've read). She's working on cases involving insurance fraud and yachts. She's on the trail of a ship named Blackbird, and Mac (former special ops) is a transit captain hired to take the yacht to get it's final bits and bobs installed. The two team up when it's discovered that others want the boat for nefarious reasons.
I enjoyed the developing relationship between the two main characters, Emma and Mac. But as the book takes place over the course of nine days--with the bulk of the book taking place over six days, and the final chapter set three days later--I had a tiny bit of a hard time believing in their HEA. HFN, for sure, though. No "I love yous" were exchanged, but the two deep form a connection based on more than just physical attraction, and I can see things working out for them in the long run. I like that there was zero angst between the two of them. They were attracted to each other, they acted on it, they worked together to defeat the bad guys.