Can You Hula Like Hilo Hattie?. Triple Threat Mysteries, #2

The novice sleuths accept their first official detecting assignment: uncovering the "secret" of an elderly millionaire's pretty young wife. If they succeed, their newly founded business, The Triple Threat Investigation Agency, will prove a viable venture. The problem? The wife is found murdered along the sapphire shores of Oahu. And there's a secret all right, one of many, but the deceased woman is not the only one keeping them. As Jill, Rey and Linda try to fit the puzzle pieces together, they stumble across several more bodies.
But who is the killer?