Now, the trailer for this didn't worry me in the slightest. A little girl who can make her drawings move? Ha! But good God, was I wrong. This episode is an incredibly clever piece of writing that actually quite surprised me.

With the benefit of hindsight, there's not a single thing mentioned in this entire episode that doesn't count towards the final outcome. The attention to detail is perfect - the '09' and '61' numberplates on the cars, the news ticker on the bottom of the TV - nothing at all gets missed. Billie Piper is outstanding as she shows just how good a sidekick Rose is, both Chloe and her mother play their parts perfectly, and David Tennant is brilliant as usual.

The idea behind the whole story is genius, and the way it pans out even had me, a hardened Resident Evil fan, feeling tense a couple of times. I'd say this is probably one of the best episodes of the series - although, to be honest, still not even a patch on The Girl in the Fireplace, which is easily the best since the show was revived.