It's 6.30 in the morning on Christmas Day. With a flutter of excitement, you unstick your eyelids and squint out into the lingering winter darkness – except it's not dark at all. The room is lit as brightly as a dentist's office, and some people seem to be, er, sleeping the wrong way up. You go to roll out of bed… and find you're strapped in. OK, this is getting weird. And where are all your presents??