Terry, the tent, grits his teeth (did you know tents have teeth?) and the children are in for an unusual day. Granny and Granddad are looking after their grandchildren for the day and Granny thinks it would be fun to put up their old tent in the garden. However, Terry has other ideas. But by the time the children's mum arrives home, everyone has had an unexpected, not to mention wonder-ifiral, megasaurus day.