The turn of the screw is one of the most celebrated stories by Henry James. It is also a top writing within the so-called fantastic literature, whose narrative strength comes from the intermittent visions suffered by the main character. The vividness and dramatic content that represent the firstly unidentified human figures, that moreover recur as brief, stereotyped and fragmentary images, are constitutive of complex visual hallucinations. These characteristics, alongside acute premonitory symptoms such as emotional changes (fear, anxiety) or altered thinking (forced, "dejà vu", "jamais vu"), and the final altered awareness or loss of consciousness, allow us to infer an epileptic nature of the ten episodes described. Postictal psychosis, that follows a lucid interval and may last up to the several weeks encompassed by the story, would account for the paranoia featured, in the setting of a temporal lobe epilepsy. The accurate descriptions prompted us to search for autobiographical, scientific or literary influences: The alcoholism and visual hallucinations suffered by his father, the knowledge on hallucinations provided by his brother Williams on his paramount and former The Principles of Psychology, and an early devotion to Poe's writings, an epileptic himself with excellent descriptions of seizures in his writings, might have enabled the author to perform his story with such a hallmark of neurological details.