After four high school friends are involved in a hit-and-run road accident, they dispose of the body and vow to keep the incident a secret. A year later, they each start receiving anonymous letters bearing the warning "I Know What … Jennifer Love Hewitt, Freddie Prinze Jr., Sarah Michelle Gellar, Ryan Phillippe, Bridgette Wilson-Sampras, Johnny Galecki, Muse Watson Added on HBO 2022-06-18. Youtube Trailer