John D. MacDonald 
Drowner [EPUB ebook] 

Lucille Hanson had rid herself of the wrong man — her rich husband who lived casually and loved carelessly. Then she found another man she hoped would be right. She was putting together the pieces of her life — until all of her hopes came to rest at the bottom of a lake, where her body was found.It must have been an accident was what most people said. It might have been suicide, was what others wanted to think. But among her mourners just one person refused to believe it was anything but murder …