Separated from the Doctor, Clara discovers a new menace from another dimension. But how do you hide when even the walls are no protection? With people to save and the Doctor trapped, Clara comes up against an enemy that exists beyond human perception.

Lately, Doctor Who has been on a string of horror episodes. This one is interesting in that it also mixes in a lot of humor, especially when it comes to a running gag of a mini-Tardis.

The bad guys themselves are pretty cool with a very nice design, and some awesome special effects. The monsters themselves aren’t much of the point in the episode though, instead acting as a driver to something bigger.

Overall though, the episode is about Clara, who has taken on the role of the “Doctor,” and must save the day. It builds on a theme of the season, building up the strength of Clara, shifting her from her role as a macguffin whose character was intertwined with the Doctor reminding him of who he was, with no other motivations. This season has changed her into an independent companion who’s as much the hero as the Doctor, and much more of a 3 dimensional character (pun intended considering the bad guys this episode). The irony being, this is her last season.

Overall, the episode continues an intriguing season with each episode having a goal, and aiming to accomplish it.

Overall Score: 8