Felix E. Feist directed this second adaptation of the novel by Curt Siodmak (filmed previously in 1944 as The Lady and the Monster and later in 1963 as The Brain), which tells the story of a brilliant brain specialist (Lew Ayres) whose attempts to save the life of an accident victim result in the extraction of the dying patients brain, kept alive via electrodes and a special solution. Before long, the disembodied gray-matter -- which previously belonged to sinister, wealthy industrialist Donovan -- begins to exert a supernatural influence over the doctor, until the once-kindly scientist begins taking on Donovans aggressive, paranoid personality traits and is compelled to carry out the brains nefarious commands. This is by far the most effective and intelligent treatment of its source material, building a creepy, suspenseful mood while avoiding lapses into pulp-novel camp. ~ Cavett Binion, All Movie Guide