Stefan, a young gay East German medical student, arrives in San Francisco 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. At the same time, a serial killer is haunting the gay bars of the city and is killing HIV positive long-term survivors.