Soprano Geraldine Farrar was a diva with a difference! She was about to play a whodunit duet with none other than the great Caruso. They made beautiful music together in operas from Tosca to Madame Butterfly. Then French baritone Philippe Duchon hit a series of low, low notes that turned the 1915 Metropolitan Opera season into a disaster, and the tenor and soprano turned their legendary talents to criminal detection.