Nine O'Clock Tide — Mignon G. Eberhart

To all appearances, the marriage of Meade and Sam Havlock had been made in heaven. But this was far from the truth. Even though Sam's wealth and fame had given Meade luxuries beyond measure, Sam himself remained aloof. And Meade cherished the memory of Andy Brooke, an old lover who had deserted her long before. Now, suddenly, horribly, Sam was dead. Murdered. And Meade herself became the prime suspect. Especially when it was discovered she was to inherit $300 million and that Andy Brooke had come back.