Diane Phipps., P.I., devotes herself to finding out who poisoned the owner of a turquoise mine in New Mexico—yet, nobody appears to dislike him enough for murder.

Who had murder on their mind? Diane Phipps, P.I., accepts a new case in Marigold Mesa, New Mexico to expose who poisoned Ethan Marlboro, owner of the Apache Plume Turquoise Mine, after a miner dies. Working with Detective Jim Diamond, questions rise. Was Rosamond Santorini, Ethan's fiancée and Diane's own client at fault? Did estate manager Rocky Michaels hold a grudge? Maybe grateful housekeeper Gloria King? Or Tiny Mackinaw, the victim's museum curator? Did ex-girlfriend Natalie Waterman gain revenge? Confronting the prime suspect rivals Diane's battle with a rattlesnake. But determined Diane soon stamps "CASE CLOSED" on the Marlboro file.