This is the second in the Brothers In Arms Security series. That said, the characters in SEAL Protector stand very well on their own, though the storyline is clearly continued from the first book (which I haven't read) and ends up with the underlying suspense plot unresolved, clearly to be resolved in the third book.
I'm not a huge fan of this sort of thing; I really prefer each book in a series to be able to stand completely on its own merits. The romance in this one does so very nicely, and it's a well-written read, but I wouldn't recommend reading it unless you've read the first and intend to read the third.
Four stars.
Disclaimer: I received a copy of this book for review through NetGalley.