Designer Katherine Watson is enjoying a delectable frozen pistachio treat at Ginardo's beachside ice cream shop when her friend issues a playful dare. Katherine can't resist accepting the challenge and finds herself tasked with creating a designer purse out of pistachio shells. But the fun day takes a chilling turn when Katherine uncovers a clue in the ice cream store to a decades old missing persons case—and she suspects there may be a killer in their midst. Katherine is soon up to her shoulder bag in danger, but she's determined to see that a murderer gets his just desserts.