Barbara comes to Italy to visit her blind sister but when she arrives she finds that her sister's been missing for weeks. Soon she gets involved with the murder of her sister's boyfriend, a mysterious diver, and another missing blind girl.
Barbara pretends to be blind in order to attract the attention of millionaire David Malcolm whom she suspects is the serial killer targeting blind girls after someone makes the found blind girl commit suicide by playing seagull noises.
Barbara is invited by David to come and stay at his private island where he lives with his controlling cousin and sinister manservant.
Frederick, David's concealed disfigured son falls in love with Barbara just as Martin, her boyfriend, comes to Seagull Island looking for her.
Barbara finds out David's darkest secret but will Martin and the police be too late to save her and the other inhabitants of Seagull Island?
