How can tomorrow ever be as good as yesterday? Boy doesn't think it can be and puts all his scientific knowledge to use, trying to work out how to go faster than the speed of light and make time go backwards. His grandad discovers him exploring the garden looking for wormholes, a possible shortcut back to yesterday - and reassures him that tomorrow will hold great experiences, which will become new treasured memories. A powerful reminder to 'seize the day'. Nominated for the Kate Greenaway Medal.