Max is horrified to find that younger brother Liam has learned nothing from their previous adventure. Once again Liam opens an app on Miss McBoob's phone, and this time the brothers travel through time. Without leaving their town they find themselves in the Stone Age, the Roman Era, the Middle Ages and finally in the age of the dinosaurs! Will they be able to work together to solve the riddles and return to their own time before the battery runs out? Or will that irate mammoth get to them first?