In 1986, Eddie and his friends are just kids on the verge of adolescence. They spend their days biking around their sleepy little English village and looking for any taste of excitement they can get. The chalk men are their secret code; little chalk stick figures they leave for each other as messages only they can understand. But then a mysterious chalk man leads them right to a dismembered body, and nothing will ever be the same. In 2016, Eddie is fully grown, and thinks he's put his past behind him. But then he gets a letter in the mail, containing a single chalk stick figure. When it turns out his other friends got the same messages, they think it could be a prank... until one of them turns up dead. That's when Eddie realizes that saving himself means finally figuring out what really happened all those years ago.