A group of friends stop to pick up a hitchhiking woman only to end up getting drugged by her with a gas. They awaken to find that vials have been implanted in the base of their skulls. They are, of course, instantly fatal if removed. A grinning, professional-looking woman informs them on TV screens that they have 22 hours to fill these vials with a specific amount of brain fluid - a fluid that is produced during times of extreme pain. Along with another...