Watch 123Movies. Soprano Yvonne Kenny turns in a spirited performance as Aspasia in this brilliant staging of composer Wolfgang Amadeus Mozart's first notable opera -- penned when he was only 14 years old. The production, set in early Roman times, follows the inner circle of the empire's most formidable foe, King Mithridates of Pontus. Maestro Nikolaus Harnoncourt conducts the sterling cast, which includes tenor Gosta Winbergh and mezzo-soprano Ann Murray.