The Last House on the Left (1972)

To avoid fainting keep repeating, it's only a movie... Only a movie... Only a movie...

On the eve of her 17th birthday, Mari and friend Phyllis set off from her family home to attend a rock concert in the city. Attempting to score some drugs on the way, the pair run afoul of a group of vicious crooks, headed up by the sadistic Krug.