Beach Party is the 10th book in the Point Horror series, and the 4th book in the series written by R.L. Stine.
Synopsis[]
It's the ultimate beach party in California. And Karen, who's just broken up with her boyfriend, is going to enjoy every minute of it--especially having two new guys who like her. But the party takes a nasty turn when Karen realizes someone is out to spoil the fun by getting rid of her.