 Peter Neal , an American writer of violent horror novels , is in Italy to promote his latest work , Tenebrae . He is accompanied by his literary agent , Bullmer and his assistant , Anne . Neal is unaware that he has also been followed to Rome by his embittered ex @-@ wife , Jane . Just before Neal arrived in Rome , Elsa , a young female shoplifter , was murdered with a razor by an unseen assailant . The murderer sends Neal a letter informing him that his books have inspired him to go on a killing spree . Neal is soon contacted by the police in the form of Detective Giermani and his female partner , Inspector Altieri . 
