Necroscope (Necroscope #1)

Harry is an English youth in school, and strange things occur as he grows up, such as a sudden increased intellect in mathematics, and the ability to fight beyond his experience after a teacher is killed. Eventually he marries his childhood sweetheart, Brenda, who slowly realizes there is more to her now-successful writer husband: that he can speak to the dead, whose collective consciences remain behind, at the location of dying.