Science writer Joe Rose is spending a day in the country with his long-time lover, Clarissa, when he witnesses a tragic accident--a balloon with a boy trapped in it is being tossed by the wind, and, in an attempt to save the child, a man is killed. As though that isn't disturbing enough, a man named Jed Parry, who has joined Rose in helping to bring the balloon to safety, believes that something has passed between him and Rose--something that sparks in Parry a deranged, obsessive kind of love.Soon Parry is stalking Rose, who turns to science to try to understand the situation. Parry apparently suffers from a condition known to psychiatrists as de Clerambault Syndrome, in which the afflicted individual obsessively pursues the object of his desire until the frustrated love turns to hate and rage--transforming one of life's most valued experiences into pathological horror.