Amorangi and Millie lost their mum. Their only clue to her whereabouts is a carving on a tree that says I'm in the past! Rescue me! To do this, Amorangi and Millie must travel up every branch of their family tree and collect an object from each ancestor they meet. They must then be back in the modern day before the sun sets, or they'll all be trapped forever in the past. But can they do it in time?

In their travels, the children experience aspects of events in New Zealand history, such as the invasion of Parihaka, the Great Depression, World War Two, the Musket Wars and the eruption of Mount Taranaki. They also experience changes in the town and landscape, the attitudes of people and the way people live their lives.