Great thriller. The summary pretty much tells the story. Mac is a transfer captain who is piloting the Blackbird until relieved by the boat's owner. Emma works for St. Kilda's and the insurance company trying to find out why expensive yachts are disappearing in "accidents". The boat is a focal point for all sorts of intrigue. It is supposed to be carrying something that could cause the destruction of an American city. The FBI, the CIA, and Russian and Georgian intelligence are all on the trail and all trying to send disinformation to the other groups. St. Kilda's gets roped into the deal but Emma and Mac are the people on the scene. Emma and Mac don't know who they can trust. The book is filled with tension and intrigue. The relationship between Emma and Mac begins as a relationship of competent professionals who need to work together. Both have been involved with intelligence with Emma at the CIA and Mac in Special Ops. But both have left that work to try to find some peace. They are strongly attracted to each other but are well able to ignore the attraction until the time is right. But the attraction was hot and so was the romance. It was also good to see some of the other familiar characters from St. Kilda's again. I am a fan of Grace and Faroe. I just wish we could have seen more of Lane.