The Missing Madonna (Sister Mary Helen #3) by Carol Anne O'Marie
 
Sister Mary Helen is sinfully good at snooping through the San Francisco fog. Now a fellow OWL (Older Woman's League) member has disappeared. The police believe Erma Duran simply flew the coop, but Sister feels a Higher Authority pushing her to investigate. A gold medal entangled in Erma's bedsprings and a cryptic clue to a Byzantine madonna deepens the mystery. By the time Police Inspector Kate Murphy joins the hunt, Sister's good intentions have already paved her way straight to the Mission District--and a hellish encounter with sudden death.
 
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