Jake arrives home from boarding school for the summer holidays of 1957. In his town, many still wear the scars of WWII, but times are changing. He soon discovers that his friends have formed a gang to fight the immigrant kids, and he is forced to join it. But then a girl in a yellow hat shows him a random act of kindness. He wants to get to know her, but she belongs to the gang of the enemy. After several failed attempts, Jake finally gets to meet her, and a secret friendship develops. Her name is Eliza.

Jake has always considered himself to be an outsider, but Eliza becomes his best friend, and he soon discovers that she is far different to anyone he has ever known. However, they are living in a town that is rife with bullying and prejudice. Staying friends will not be easy. Jake's mentor, Ben, tells him that it is up to his generation to bring their divided community together, but Jake thinks that is an impossible task to give to twelve-year-old kids.

Each gang has its own jetty, and a crisis develops when one of the jetties is about to be demolished. The town bum, who people think is mute, tries to save the jetty but becomes the subject of a police siege. Jake and Eliza bring the gangs together, and they come to his aid.

The story is told some sixty years after the event and tells how Eliza's single act of random kindness eventually changed many lives for the better.