The daughter of a wealthy industrialist Joan Pratzen suffers a strange disease agnosia. Her eyes and ears are fine, but the brain is not able to form intelligible audio-visual images based on the signals from the outside world. Moreover, only she knows the important industrial secret, inherited from her father. Soon she becomes the victim of an elaborate conspiracy, which aims to wrest the secret from Joan taking advantage of her illness. Unfortunately, the girl exhausted by the disease can not determine the identity of the attacker. It can be her fiance Carles or a young and impetuous servant Vincent...