“Doctor Who” Christmas special will see Matt Smith appearing for the last time as the Doctor, leaving the role to the Twelfth Doctor, Peter Capaldi. BBC has released the trailer for the highly anticipated special episode titled “The Time of the Doctor,” which is due to air on Boxing Day in Australia and New Zealand.

The Eleventh Doctor’s companion, Clara Oswald (Jenna Coleman), narrates the 35-minute clip, with another woman claiming that the “siege of Trenzalore is now begun.”

The Doctor is expected to die in Trenzalore and be regenerated into a new body.

“Orbiting a quiet backwater planet, the massed forces of the universe’s deadliest species gather, drawn to a mysterious message that echoes out to the stars – and amongst them, the Doctor,” the synopsis for the episode reads.

“Rescuing Clara from a family Christmas dinner, the Time Lord and his best friend must learn what this enigmatic signal means for his own fate and that of the universe.”

Fans of the youngest and only Doctor nominated for a BAFTA Best Actor award were understandably heartbroken over his departure, but none were as sad as Smith’s own mum.

“My mother is mortified honestly, she was at the front of campaigning for me to stay,” he said. “And she wasn’t happy when I said I was going to leave. But when you gotta go, you gotta go.”

His last episode is also a “bitter sweet” one for him as well, saying “It’s very sad for me in many ways because everything is the last time. It’s the last read-through, the last time I put on the bow tie and the last scene in the TARDIS.

“But the show is about change and I had lunch with Peter Capaldi shortly after the announcement and I think he’s just going to be incredible. He has the most brilliant ideas. As a fan, I’m genuinely excited to see what he’s going to do because I think he’s going to do something extraordinary.”

“The Time of the Doctor”