“Doctor Who” Season 9 is almost over, and it’s finally heading home. The season finale finds the Doctor (Peter Capaldi) back on Gallifrey, but it isn’t a warm homecoming. At the end of episode 11, the Doctor returned to his home planet and told a child to alert the city of his arrival. In episode 12, titled “Hell Bent,” the Doctor will go up against the other Time Lords.

“If you took everything from him, betrayed him, trapped him and broke both his hearts…how far might the Doctor go?” the episode 12 synopsis asks.  “Returning to Gallifrey, the Doctor faces the Time Lords in a struggle that will take him to the end of time itself. Who is the Hybrid? And what is the Doctor’s confession?”

In the last episode, the Doctor claimed he was the Hybrid. “The Hybrid destined to conquer Gallifrey and stand in its ruins is me,” he said. But the synopsis makes it sound like a mystery that still has to be solved. Is the Doctor wrong?

Ashildr (Maisie Williams) -- or whatever she'll be calling herself now -- will appear again in episode 12. The former human was turned immortal by the Doctor. Could she be the Hybrid? In the trailer, she makes it seem like it could be. “I think it’s time to tell the truth,” she says.

The trailer also shows a regeneration, but is it the Doctor? Capaldi hasn’t made any announcements about leaving, and with an entire planet of Time Lords, anyone could be getting a new face.

Watch the “Doctor Who” Season 9, episode 12 promo video below:

The international trailer doesn’t give many more hints. However, it does reveal a Weeping Angel and a Dalek, so it seems the Doctor will face many of his enemies this week. Watch the promo video for the “Doctor Who” Season 9 finale below:

“Doctor Who” Season 9, episode 12, airs Saturday at 9 p.m. EST on BBC America.