James is a 17-year-old who believes he is a psychopath. He kills animals as a hobby, but grows bored with that and decides to try killing a person. He settles on Alyssa, a mouthy, rebellious classmate with issues of her own. She proposes that they run away together, hoping for an adventure away from her turbulent home life, and James agrees with the intention of finding an opportunity to kill her. They embark on a road trip across England and develop a relationship after a series of mishaps.
