If you thought the "Sherlock" Season 4 premiere was dark, hold on for dear life. According to showrunner Steven Moffat, things are going to get even worse -- and yet also funnier? -- in the second episode.

SPOILER ALERT: Stop reading if you haven't seen the premiere.

In "The Six Thatchers," Mary Watson (Amanda Abbington) took a bullet for the grandstanding Sherlock Holmes (Benedict Cumberbatch), leaving John Watson (Martin Freeman) in anguish, from a mix of personal guilt and anger at Sherlock.

Moffat told Entertainment Weekly that the core of the show will always be Sherlock and Watson, so Mary had to get out of the way so they could "reset to the most traditional and famous version of the format." He said, after the premiere, they don't ignore the Sherlock/John rift. "If anything, the rift gets worse. We decided if we were doing this we're doing grief properly. We were doing the consequences properly. We tried to have people go through what they'd actually go through in this circumstance which, of course, is hellish."

Moffat said they debated whether to kill Mary in Episode 1 or the more traditional Episode 3, which ends the season. EW basically asked if the rest of the cast should consider themselves safe in the next two episodes. Here's what Moffat had to say about that, teasing the darkness ahead:

"Anything can happen to anyone. I think it's safe to say we couldn't do Sherlock Holmes and Dr. Watson without Holmes and Watson. But nobody's safe and consequences are everywhere and there's some emotionally grueling stuff coming. There's proper humor too. We showed Episode 2 to some people and though it's the darkest one we've ever done there were still people laughing."

Episode 2, "The Lying Detective," was written by Moffat and airs Sunday, January 8 (opposite the Golden Globe Awards). Episode 3, "The Final Problem," will end the always-too-short season.

What could happen in Episode 2 to make it the darkest they've ever done? The synopsis reads, "Sherlock squares off with Culverton Smith (Toby Jones), a chilling enemy with a very dark secret." It airs Sunday from 9 to 10:37 p.m. ET on PBS.

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