According to a report in The Radio Times, while Doctor Who series 13 filming is already underway, we still don’t know a lot about the continuing adventures of Jodie Whittaker’s Thirteenth Doctor.

Sure, we know John Bishop is joining the gang as Dan and we’ve heard a few rumours about returning monsters and Jodie Whittaker’s potential exit, but overall the new episodes have been kept pretty much under wraps, leading eagle-eyed fans to look all the harder for any hints or details online.

And now they might have found something. Deep in the recesses of the internet, a few Doctor Who fans have unearthed a synopsis for a planned graphic novel tie-in, written by regular Who comic scribe Jody Houser and illustrated by Roberta Ingranata.

The reason for its significance? The story stars John Barrowman’s Captain Jack Harkness – and apparently it ties in directly with series 13’s second episode.

“A thrilling new Doctor Who Graphic Novel which stars fan-favourite Captain Jack Harkness as he goes up against the insidious Torchwood institute!” the synopsis reads.

“In the midst of kicking alien butt – and looking good doing it – Captain Jack Harkness is suddenly transported through a time-window to 19th Century Cardiff… again! Realising there’s more than one thing afoot, he sets out to uncover what the Victorian-era Torchwood Institute team are up to behind closed doors, hoping to solve the mystery of why time-windows are cropping up everywhere.

“But what he finds is very unexpected, and will certainly leave him needing a hand from some old friends…

“Bursting straight out of the long-running hit television series, this bold new tale ties in directly with episode two of the hotly-anticipated series 13. Buy it, read it, then travel back in time to read it for the first time all over again…!”

The synopsis was originally found on the official Penguin Random House website, and while it has since been removed it is still publicly available to view on other sites. When contacted the BBC declined to comment on “speculation.”

But of course, this synopsis does open up some intriguing possibilities – perhaps most notably the potential return of John Barrowman’s Captain Jack Harkness for series 13. In some ways this wouldn’t be too big a surprise given that Barrowman reprised his fan-favourite role in series 12 and (more extensively) the 2021 New Year’s special Revolution of the Daleks, but it’s the first real hint that Jack could be back again since the Doctor waved him off in January.

Alternatively, it could be that the “tie-in” to episode two is working slightly differently, with Jack thrown onto the fringes of a story that he’s not necessarily a huge part of in the main series. Perhaps the Victorian setting of the graphic novel crops up in the series, or maybe this story is a prequel to episode two, shortly before another surprise return for the galaxy’s most charming Time Agent.

Then again, it could be that the “time windows” sending Jack back in time are the real issue to watch here, rather than Jack himself. Who knows? Perhaps some incident causing the “time windows” is a crucial storyline in series 13, with gaps in space and time opening all over the place and kicking off adventures in other stories and spin-off media (i.e. this Jack story could be just one of many similar spin-offs). With that in mind, Jack might not be back in the main series at all.

Still, whether it’s a plot-related or character-based spin-off from the next series, one thing is for sure – series 13’s second instalment looks to be like an episode worth watching. If only we had our own time windows to jump ahead and watch it…

Doctor Who returns to BBC One later this year.