Who is Sam Keatley from The Spy's Wife and what is their importance?

Sam Keatley is Molly's husband, who is employed as a journalist at The New Technocrat newspaper. Secretly, Sam is actually a Russian spy. He is described as short and stocky, with grey hair and blue eyes. Over the course of the novel, the reader comes to see Sam as a selfish, thoughtless man who has not only repeatedly lied to his wife, but also placed her in great danger. In the end, we learn that Sam is far different than the man we've perceived him to be. Not only is he charming, humorous and likeable..... he also loves his wife. Unfortunately, Sam is killed at the end of the book.