Detective Inspector Humphrey Goodman and his team are left stumped when millionaire environmentalist and scientist Dan Hagen is shot on his boat while out at sea. The evidence seems to point to a robbery gone wrong, but with no other boats reported in the area, Goodman suspects a member of Dan’s team, his wife of nine months, his ex-girlfriend, his scientist partner and a research graduate who were diving together in plain sight of one another at the time of the murder. A metal toy soldier with no fingerprints found at the scene is the only clue.