Pig (Cillian Murphy) and Runt (Elaine Cassidy) are two inseparable friends who were born on the same day, minutes apart, in the same hospital. They spend all their time together, speak their own private language, and even join together in various criminal pursuits. However, as their 17th birthdays approach, Pig's sexual awakening brings about a crisis in their relationship, one which can only be resolved in violence and destruction.