San Francisco is preparing for the premiere of a new staging of the Puccini opera, Turandot. The passionate story of the Chinese princess Turandot, and the mysterious three riddles which are the key to her heart, are on the lips of opera buffs throughout the city. At the same time, a serial killer is haunting the gay bars of the city and is killing HIV positive long-term survivors. Stefan, a young gay East German medical student, arrives in the city for a medical congress and is following the trail of his dead father, a once high ranking AIDS researcher in the East. Stefan is investigating whether the HIV virus was an incremental result of secret human experiments that were conducted in US prisons in the seventies - a thesis of the Berlin professor Jakob Segal, which was spread by state agents of former East Germany. Secret lists involving these biological experiments are rumored to have surfaced in San Francisco.