The latest episode of Game of Thrones had a lot to take in, from an epic battle to loads of little call-backs - but it may have also featured a secret cameo.
Eagle-eyed fans have pinpointed what they believe is the ghost of a long-deceased character hidden in the episode.
Spoilers for Game of Thrones S07E04 follow.
In the episode, entitled The Spoils of War, Arya returned to her hometown Winterfell and reunited with her siblings Sansa and Bran.
- The best Twitter reactions to that Lannister / Targaryen battle
- The real meaning behind Arya's reunion with Nymeria
While in the northern castle, she also sparred with Brienne - the warrior who took an oath to protect her and Sansa for their mother, Catelyn.
As Arya mentions her mother in the scene, a figure walks past in the background that resembles Catelyn - albeit with ample wintry clothing on and her head down so as viewers can't see her face.
So while it's impossible to say if it definitively is the ghost of Catelyn, the timing of her walking past at the very moment her daughter mentions her - in their mutual home - is a strong coincidence.
What looks to be the same person also walks past in the background again later in the scene.
The next episode of Game of Thrones airs in New Zealand on Monday, August 14.