Isla Muir, a former marine biologist, has taken over her late father's charter boat business on the west coast of Scotland. While she longs to complete her unfinished research, she finds it difficult to move on from her hometown. As she ignores cleaning her father's house, Isla focuses on the charter business, which mostly brings scuba divers out to the cold, dark waters off the coast. When an American scientist, Casper Shaw, pays her for a private charter, her passion for research returns. Feelings surface between Isla and her customer. Casper Shaw isn't all he claims to be. Yes, he is an American. Yes, he is a scuba diver. Yes, he is undeniably sexy. What he's really searching for, Isla discovers, is retribution. Will Casper find what he wants, or what he needs?