Whatever’s going to happen in the upcoming fourth season of BBC’s Sherlock, it seems like the title character and his small group of friends aren’t going to be having a lot of fun. That especially seems to be the case in the show’s latest teaser, which echoes the “It’s not a game anymore” tagline from the last one and presents Benedict Cumberbatch’s Holmes with a tough question: “What’s the very worst thing you can do to your very best friends?” Holmes’ response—or at least what this teaser frames as his response—may seem unexpected, but considering the thematic points this show has been making for several seasons now, it’s not especially surprising. What Holmes actually means by his comment, though, remains to be seen.

Season four of Sherlock will premiere on January 1 in both the United States and the U.K.—an overdue first for the series.