I love J.D. Robb's In Death series, and NAKED IN DEATH is the book that started it all back in 1995. Now there are 40 books in the series, and it just keeps getting better. Eve Dallas is a kickass heroine who is pretty much a loner in this first book. She gets involved with Roarke, who is a suspect in a murder investigation, and neither of their lives will be the same again.
This is a series you read in order, as each one builds on the relationships in the previous books. You could read them out of order, but why would you? They're all amazing and well worth the read.
In a world of danger and deception, she walks the line--between seductive passion and scandalous murder...
Eve Dallas is a New York police lieutenant hunting for a ruthless killer. In over ten years on the force, she's seen it all--and knows her survival depends on her instincts. And she's going against every warning telling her not to get involved with Roarke, an Irish billionaire--and a suspect in Eve's murder investigation. But passion and seduction have rules of their own, and it's up to Eve to take a chance in the arms of a man she knows nothing about--except the addictive hunger of needing his touch.