The Loner is Rhonda Nelson's latest in a series called Men out of Uniform. Lucas "Huck" Finn is a former Army Ranger who joins Ranger Security after leaving the service. Huck's first assignment is to babysit heiress Sapphira Stravos. Sapphira's father has been receiving threatening notes that Sapphira is in trouble. Sapphira doesn't want a bodyguard because she is afraid her father will find out how she really spends her days. Sapphira and her friend Cindy Ward have started a charity called Belle Charities. Sapphira tries to get rid of Huck by trying to act like a "spoiled little rich girl", who shows no concern for those around her, spending her days shopping, and carting her little dog around to various appointments. Huck gets the upper hand when he puts Sapphira under house arrest. Of course, you can feel the chemistry between them from their first meeting.
Huck and Sapphira try to fight their attraction for each other, but eventually give in to the passion. Huck also can tell that there is more to Sapphira than meets the eye. He continues to search for search for the writer of the letters even as he begins to fall in love with her. Huck and Sapphira find a way to make the differences in each of them work together to form an explosive, sexy relationship.