Broken Date (Vintage Paperback) by R.L. Stine

A DATE WITH DEATH

Jamie and Tom are in love. They've gone steady since junior high, and are planning to graduate from high school and attend college together. Then, of course, they'll marry. Everything's perfect until Tom breaks a date-and all the horror begins.

Suddenly her perfectly planned dream has become a nightmare. She must talk to him. But what has happened to Tom? To Jamie's horror, the boy she loves is stalking her, calling her, threaten-ing her. Tom can't afford to let her live. And there's nowhere she can hide....