Serum obtained from a brain after a mass murder transforms the good Dr. Jekyll of London into the evil Mr. Blood. Serum obtained from a brain after a mass murder transforms the good Dr. Jekyll of London into the evil Mr. Blood. Serum obtained from a brain after a mass murder transforms the good Dr. Jekyll of London into the evil Mr. Blood. Serum obtained from a brain after a mass murder transforms the good Dr. Jekyll of London into the evil Mr. Blood.