Potential spoiler alert! Even though Christopher Nolan is looking to keep the secrets of The Dark Knight Rises locked down as tightly as he can, with the film now shooting out and about around the world, things are starting to leak. One such element broke free of the Bat-Security Web last night, with a particular piece of casting revealed when the person involved showed up on the London set. To preserve the mystery, we won’t say who for a couple of paragraphs, so if you don’t want to be spoiled, do not click the link below and leave the page now.

The Dark Knight Rises already features the likes of Christian Bale, Michael Caine, Tom Hardy, Morgan Freeman, Gary Oldman, Marion Cotillard, Juno Temple, Josh Pence, Anne Hathaway and Joseph Gordon-Levitt. And while the plot is still a guarded secret, we do know that Hardy is playing the villainous Bane and that Hathaway is on board as Selina Kyle/Catwoman.

But even more intriguing is The Social Network’s Pence, who is on to play a younger version of Ra’s Al Ghul, the crafty villain first seen in Nolan’s universe in Batman Begins. Liam Neeson played him then, and Hitfix got a tip that Neeson has been seen filming scenes for Rises.

Since Al Ghul seemingly died at the end of Begins, there’s no word on whether this is a flashback or whether he’s been resurrected. But the character is famous for having the Lazarus Pits, which have been used in both the comics and the cartoon series to bring him back. They’re a little more supernatural than the realistic tone Nolan and co have taken, but they’re not outside the realm of possibility and sets that look very much like the pits have been spotted before.

We’ll have to wait and see exactly what Neeson’s appearance means, but it’s definitely an intriguing conundrum to ponder…