Light Jar by Lisa Thompson

Nate and his mother are running away, hiding out in a tumbledown cottage in the middle of a forest. When Mum heads off for provisions, and then doesn’t return, Nate is left alone and afraid, with the dark closing in all around him.  But comfort can come from the most unexpected of places – an intriguing girl on a mission to solve a decades-old treasure hunt, and the reappearance of an old friend from his past…