Warning: This post contains spoilers through episode three of season seven of Game of Thrones, and predictions about major plot points in future episodes. If you are not caught up, stop reading now.

As we noted before the seventh season of Game of Thrones began, the internet has been abuzz with fan theories about the fate that might await the sneaky Petyr “Littlefinger” Baelish. But one easy-to-miss moment in the latest episode may have hinted at new dangers for Westeros’s raspiest royal whisperer, and a new theory explains how it might lead to Littlefinger’s downfall.

The theory comes courtesy of The Ringer’s Jason Concepcion, who runs the Ask the Maester blog. He set out to explain a curious double-take Littlefinger did when a maester at Winterfell revealed that his predecessor, Maester Luwin, kept “a copy of every raven scroll.” So just what about old raven scrolls would make Baelish so jumpy?

Concepcion goes back to one of the show’s earliest unanswered questions for the explanation: Could Littlefinger have had something to do with the unexplained assassination attempt on Bran Stark in the series’ second-ever episode?

The would-be assassin was carrying a Valyrian steel dagger known as the “catspaw blade” or “catspaw dagger,” an exceedingly expensive and uncommon weapon. Presumably, whoever called the hit wanted the murder to be readily traceable. Catelyn Stark carried the blade to King’s Landing to show Ned and warn him that there was treachery afoot. But Littlefinger just so happened to catch a glimpse of the knife, and casually mentioned that it was once his, before he lost it to Tyrion Lannister in a bet.

Murdering a child to turn the Starks and Lannisters against each other certainly doesn’t seem out-of-character for the always-scheming Littlefinger. In fact, according to Concepcion, the idea fits Baelish’s mantra of “create chaos, climb the ladder” perfectly.

If Baelish was indeed behind the assassination plot, Concepcion predicts that there will be a paper trail in Maester Luwin’s old raven scrolls that could expose his duplicity. That might explain why Sansa is seen looking surprised at a raven scroll in the preview for episode four. (Here are a couple of other details you might have missed from the teaser.) And if it has anything to do with why Arya Stark was carrying the catspaw blade on the cover of Entertainment Weekly, Littlefinger’s days might be numbered—and his death might come at the hands of the surest assassin in Westeros.