Shrouded in mystery by modern standards (no plot leaks, no full
cast list, a vague trailer, just a few photos, quotes about how unusual it is)
this episode has been the subject of assorted rumours in the week leading up to
today. You know what, this is a good and rare thing these days. When even teaser
trailers can ruin some surprises it makes a pleasant change to approach
something with no real knowledge of what is about to unfold. Pre Internet, pre
smartphones most things were like this, now its very difficult to keep secrets.
If you’ve seen the episode, you'll know it's worth watching without knowing what happens so if you haven't then the review that follows reveals things...
Spoilers ahoy after the break
