Every lonely monster needs a companion...

Prerequisites: Nothing specific, but there is a reference to The Impossible Girl arc, for which you'll need the previous bits of Series 7 to understand. The rest of the episode is stand-alone though.

Spoilers!
I quite like Hide, and I think it's one of the better episodes of Series 7. For starters, I really like the concept; ghost hunting has always been a fun activity to watch in media, and combining that with Doctor Who seems natural. The setting and atmosphere here are suitably creepy, and I even love the entire concept of this shadowy pocket dimension. The side characters aren't anything amazing, but I think they're suitable (and the love story is cute). Really, the only major complaint I have is that the last-minute of Hide simply doesn't need to exist. From browsing the wiki, it seems like this was tacked on later to emphasize the story's themes, but I honestly think it retroactively weakens the story by portraying The Crooked Man as nothing more than a lovesick creature. In a way, not only does it posthumously remove tension, but it also renders certain story beats confusing (like why The Crooked Man would bother with scaring the Doctor in the first place). Still, I very much enjoy the rest of this episode. It's nothing amazing, but this is a very solid time.