Doctor Who fans spot hidden treasure hunt and look to Find the Doctor

It's been an exciting weekend for fans of Doctor Who, with the release of a series 13 trailer and the announcement that Game of Thrones star Jacob Anderson would be joining the cast as a mysterious character named Vinder.

But it looks like even more Doctor Who news could be in store – if fans can solve a cryptic clue hidden in the trailer.

Richard Lloyd posted on Twitter that the word 'mystery' was written in the trailer's first frame, and added that it took you to a dedicated site, www.doctorwho.tv/mystery.

"Welcome to a mystery across space and time," the site teases. "Work together to solve the hiDden clues and reveal a password below. #FindTheDoctor.

"It begins: 13:13.13."

So far, it looks like the password is yet to be cracked, with many fans taking to Twitter to work on finding out exactly what this mystery is all about – and what they might discover if they manage to solve it.

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It's been a very eventful weekend for Whovians after the announcements made in San Diego ComicCon@Home.

On top of a new trailer for season 13, the TARDIS team spoke at length about what fans can expect when the classic Sci-Fi show returns later this year.

Speaking about the upcoming series, showrunner Chris Chibnall said: "Yeah, a lot of cliffhangers this year. There's a couple of my favourite cliffhangers that we've done this year. I think you'll know [them]..."

The coming series will also be entirely serialised in an ambitious move for Nu-Who.

Doctor Who returns to BBC One later this year. Want more? Check out our dedicated Sci-Fi page, the RadioTimes.com Doctor Who podcast‘s latest episode or visit our full TV Guide for more picks and listings across every channel