The physician is unable to save Donovan's life, but removes his brain on the chance that it might survive, placing the gray matter in an electrically charged, oxygenated saline solution within a glass tank.

The brain uses Cory to do his bidding, signing checks in Donovan's name, and continuing the magnate's illicit financial schemes.

Realizing he will soon have no control over his own body and mind, his assistant, Schratt, devises a plan to destroy the brain during its quiescent period.

Schratt resists the brain's hypnotic power by repeating the rhyme, "Amidst the mists and coldest frosts he thrusts his fists against the posts and still insists he sees the ghosts."

Schratt destroys the housing tank with an axe and leaves the brain of Donovan to die, thus ending his reign of madness.

[6] The novel has been adapted for the screen three times – in 1944 as The Lady and the Monster (later re-issued as Tiger Man), in 1953 under its original title, and in 1962 as Vengeance (later reissued as The Brain).