Day I Found a Wormhole at the Bottom of the Garden

Nine-year-old Billy is digging for buried treasure when he finds a wormhole in the garden! And to make matters worse, all sorts of people from the past begin to clamber through it. Now Billy - aided by his pet dog, Shakespeare - is in a race against time to close the wormhole and round up all the people who have slipped through it, before history is changed for ever! No pressure then?