In Season 8 Episode 9 of "Doctor Who" entitled "Flatline," the opening scene showed a man who was sucked into a dark void and was later shown as part of a wall décor. The Doctor and Clara noticed that the door of the TARDIS had shrunk to one third its original size.

They managed to get out and realized that the TARDIS had indeed grown smaller. The Doctor went back in and asked Clara to check what happened. When she returned, the TARDIS looked like a small toy, although the shrinkage seemed only to be on the outside.

The Doctor gave Clara his sonic screwdriver and psychic paper so that she would be able to explore. She met Rigsy, a kid doing community service who told her that several people have been lost. When they went to an apartment where people have been disappearing lately, Clara was sucked into the floor by a 2D monster, and her nervous system showed up on the wall.

The Doctor finally figured out that the monsters he initially thought to be friendly were from a 2D universe. Meanwhile, the murals slid from the walls and went after the workers. They got trapped until the Doctor managed to restore the 2D objects back to their 3D configuration.

The 2D monsters were also making themselves 3D, and during the ruckus, a community worker sent the TARDIS down a tunnel and onto a train line. With no time to spare, the Doctor put it in siege mode, which turns the TARDIS into a cube. Clara asked Rigsy to draw a fake door and managed to get the monsters to work on it. The monsters pushed through the fake door into a wall and into the TARDIS, which miraculously got back to its original size. The Doctor finally was able to get out. The 2D monsters were actually getting their energy from the TARDIS.

In Episode 10, entitled "In the Forest of the Night," the Doctor will find himself in a forest that suddenly appeared in London as he takes some students of Clara and Danny out on a field trip.

According to MStarz, the new episode's title comes from "The Tyger," a poem by William Blake and that there will literally be a young girl wearing a red riding hood.