Dr. Gustav Niemann, who has been imprisoned for 15 years because of his gruesome experiments, escapes from Neustadt Prison with the help of Daniel, a psychopathic hunchback killer. They join Professor Lampini's traveling Chamber of Horrors, and murder Lampini, taking his place. Niemann seeks revenge against those who put him in prison. In Reigelburg, Niemann brings Count Dracula back to life, and the count murders the Burgomaster and nearly kills his granddaughter. Abandoned by Niemann, Dracula is destroyed by the first rays of daylight.
Daniel gives shelter to an abandoned gypsy girl and they search for Frankenstein's diary and discover the frozen bodies of the Frankenstein Monster and the Wolf Man beneath the ruins of the Frankenstein castle. The entire group returns to Niemann's old laboratory, where the doctor murders two old enemies and removes their still-alive brains, intending to place them into the skulls of the Wolf Man and the Monster. But the Wolf Man is killed by the gypsy with a silver bullet after attacking her. Daniel blames Niemann for her death, and strangles him, but the Monster kills Daniel. A mob of villagers pursues the Monster and Niemann into a nearby quicksand and they both sink out of sight.