Torch wielding villagers descend on the castle keep of a tyrannical Count. The Count's zombie gorilla minions keep the villagers at bay, long enough for the Count to swallow poison. Days later, distant relatives of the Count claim his body from the celebrating villagers. The Count's relatives are revealed to be masquerading zombie gorillas. The Count's body is placed in an electrostatic thermo-cylinder, then shipped overseas, to America. There, a Professor Rundhaven performs a miraculous operation that separates the Count's still living brain from his lifeless corpse. For his services, the Count repays Rundhaven with a quick death by psychic electrocution. Anxious to greatly expand his burgeoning mental abilities, and also escape the tank his brain now resides in, the Count makes plans to steal certain papers from the famous American brainwave scientist, Ralph Ervin. The disembodied brain enters into the dreams of Ervin's sleeping daughter, Susie. Influencing her to rise from her slumber, Susie is told to gather her father's paperwork on cerebro-static power absorption. The brain's intrusion into Susie's dreams, however, has not gone unnoticed. From the Dream Dome, the Sandman witnesses the ghastly horror intruding on the sleeping girl's mind, and jumps into the Dream Stream to confront it. Susie is ordered to leap off a cliff, in the dreamscape. While the Sandman is occupied with Susie's rescue, the brain withdraws from her mind.
Susie awakens from her encounter with the Sandman and the Count's brain, and relays her fears to Ervin, who writes the whole tale off as a bad dream. Having failed to achieve his goal through his psychic prowess, the Count sends two of his zombie gorilla minions to Ervin's home, the following night. Maintaining his watchful eye on Susie, the Sandman interrupts her dream to broadcast an emergency warning, directly into her brain, regarding the ape intruders. Susie bolts awake and runs to tell her father what is happening. Once more, her fears are dismissed as just another bad dream. Ervin is clubbed into unconsciousness by a zombie gorilla, as he is exiting Susie's bedroom. Where the brain failed, the zombie gorillas succeed, retrieving Ervin's papers, and returning with them to the Count's brain. The zombie gorillas are next sent out to collect certain scientific equipment the Count needs to reach his goal. Their theft, however, is witnessed by the night watchman, who contacts the police. In short order, New York's finest are storming Rundhaven's home. They have arrived too late. The Count has finished his power expanding experiments. Though the zombie gorilla minions fall in a hail of police gunfire, the officers are no match for the Count's brain. A barrage of psychic lightning lays them low.
Having grown to enormous proportions, the Count's disembodied brain moves out over the Bronx skyline. It's destination, the power station. As it nears, the police prepare to bombard the brain with six million volts of electricity. Realizing that attack will only make the brain stronger, the Sandman leaps into the waking world to try to prevent the police from striking. The Sandman's warning is rebuffed, prompting him to put one of the officer's to sleep with his Dream Sand. The assault ends with the Sandman arrested and incarcerated. The attack goes off, but the brain absorbs it all, and more, draining away all the power, blacking out the Bronx. Using his hypersonic whistle, the Sandman summons his aides, Brute and Glob. The two freakish assistants put the desk sergeant to sleep, then torment his slumber with unleashed horrors from their bag of nightmares. Releasing the Sandman from jail, Brute and Glob return to the Dream Dome. The Sandman goes to confront the, now monstrous, brain. The Count's psychic abilities have grown to the point that his brain can manifest horrific creatures out of thin air. One such horror attacks the Sandman, who defeats it with a face full of Dream Sand. Having no other recourse, the Sandman sets his hypersonic whistle to it's highest frequency and blows. The super-shrill ultrasonic vibrations play across the massive brain's surface until it explodes with near atomic fury. The Sandman reconciles his decision to end the brain's life by noting that there was, simply, no other choice.