It's 2032 and Britian is facing yet another heatwave. Temperatures are breaking all records, and a new government curfews are in place to ensure people stay indoors out of the sun, but it is also the school holidays and Polly Carraway is fed up. When a late night beach swim goes wrong she's relieved to be sent away, with her troubled brother Joel, to stay with their aunt, whose house is on the banks of a reservoir. On arriving Polly is shocked to see Truthwater Lake is drying up. As the water levels drop, a lost village emerges and even here in the countryside it is still too hot to sleep. Swimming in the lake a midnight, Polly dives down and is suddenly able to breathe, to touch rooftops and see gravestones and hear birds sing... has Polly found a gateway to the past?