It's February 1974 and working class families have been hit hard by the three-day week. The reduced power usage means less hours for people to work, and less money to get by on. Thirteen-year-old Jason feels the struggle keenly.

Ever since his parents died, it's just been him and his older brother Richie. Richie is doing his best, but since he can't make ends meet he's been doing favours for the wrong people. Every day they fear they won't have enough and will have to be separated.

One thing that helps distract Jason is the urban legend about a beast in the valleys. A wild cat that roams the forest, far up the river from their bridge. When Jason's friends learn of a reward for proof of The Beast's existence, they convince Jason this is the answer to his and Richie's money problems. Richie can get himself out of trouble before it's too late and the brothers can stay together.

And so a quest begins. Starting at the bridge of their village and following the river north, the four friends soon find themselves on a journey that will change each of them ... forever.