WhenthefabulousMoonstonediamondisstolen,allthesuspectsappeartohavealibis.Eventheyounggirlwhoownsthediamondwon'tsaywhomshesawtookit.HerfianceecallsinthefamousSergeantCufftosolvethecase,butthey'llhavetountangleaskeinofliesandretrievelostmemoriesbeforethey'llfindthepathtothediamond.