After experiencing a murderous Christmas and Valentine's Day with love interest Shannon O'Hara, Detective Nick Spinelli assumed Saint Patrick's Day couldn't be any worse. He was wrong. While out on a geocaching adventure in Door County, Shannon and her friend Anna find more than a clue in the cache box. When Shannon disappears, Spinelli is sent racing to find her. Amidst the chaos of an unruly Irish celebration, and a decades-old Irish family feud, he must rescue her from the hands of a madman.