This episode features a chilling letter from Dimitri to Dr. Pavlov, recounting a 1949 Soviet experiment where prisoners inhaled a gas to stay awake, leading to horrific mutilation and the belief that entities wait in sleep. Dimitri reveals he smuggled a vial of this gas to America, where his wife Anna accidentally inhaled it to cure her insomnia. Now, she exhibits the same terrifying symptoms as the original subjects, convinced that malevolent forces are watching from behind her eyes, leaving Dimitri desperate for a cure.