Margaret Truman is getting better with each book. Here she's gone beyond the limiting format (that was getting annoying in her previous books) of having a tough-as-nails but cuddly-as-a-kitten heroine solve the crimes. The plotting in "Embassy Row" is much more carefully crafted, as British Ambassador Geoffrey James dies after his own party under mysterious circumstances. This is the first of Truman's books where you won't have guessed the villain by about 50 pages in. The characters are a bit better, but Truman's efforts at cop-talk and cop-walk still fall woefully short. Hero Sal Morizio makes lots of dumb naive mistakes for a veteran big city detective. He's the least credible of all the characters. Truman also plays some of the same riffs as in her previous books: she spends a lot of time describing D.C. cafes and restaurants, but is woefully uninformed about how government offices actually operate. For example, there is no "British Liaison office at the State Department", and CIA isn't called "the Company" by anyone but callow writers. But the very worst and most annoying mistake in the book is Truman's repeated and insistent assertion that Iranians are Arabs. They aren't, they're Muslim but not Arab.
Overall, "Embassy Row" is better than "Supreme Court" or "White House", but there's still lots of room for improvement.