LOS ANGELES — There’s still no air date set for the fourth season of “Sherlock,” but in a new interview with Entertainment Weekly, notoriously tight-lipped co-creator Steven Moffat did offer some vague clues to tease fans.

“There are some answers coming to questions nobody has asked,” he said. “We’re very exultant about a little thing we’ve set up that no one is talking about.”

That statement follows his cryptic remarks from backstage at the 2014 Emmys, when he told reporters, “We have a plan to top [last season], and I do think our plan is devastating,” he said. “We practically reduced our cast our tears by telling them the plan.”

Diehard fans of the show are sure to be “desperate for series 5″ after they’re through with four, he said. “We’re certainly going to put them through the mill. It’s going to be more of an emotional upheaval,” he said.

In the interview, Moffat also discussed how this coming season will be different from past seasons, how he feels about Sherlock/Watson fan fiction and the possibility of a “Doctor Who”/”Sherlock” crossover.

Moffat explained that each season of “Sherlock” has a different theme. “The first series was all about the beginning of their friendship. Second about the formative stages, the love and fear and loss and all that. The third was good days, me and my pal and my pal’s wife,” he said.

“[Season 4] is going to be … I suppose you’d say … consequences. It’s consequences. Chickens come to roost. It’s dark in some ways — obviously it’s great fun and a Sherlock Holmes romp and all that — but there’s a sense of … things … coming back to bite you,” he added.

The showrunner addressed the fan fantasy of a crossover episode for the two series he oversees: “Sherlock” and “Doctor Who.” Moffat said he’s more open to the idea of the merger than the rest of his colleagues. “If people want to, we should give it to them,” he said. “But I got persuaded by Mark, Benedict, [executive producer Sue Vertue] and Martin saying, ‘Look, it will never be as good as they think it’s going to be,’ and then I say, ‘Yes, but we’ll just bang it out and make it as good.’ ‘Yeah, but you can’t give everybody everything they want all the time.’ I’m in the camp of giving them everything they want. But I think they’re sane and right and I’m just a tart.”

As for the abundance of fan fiction that places Benedict Cumberbatch’s Sherlock and Martin Freeman’s Watson in, um, not-so-elementary situations, Moffat won’t disparage it. “It’s creative and exciting,” he said. “I refuse to mock it — because I’m a man who writes Sherlock Holmes fan fiction for a living!”

Before season four of “Sherlock” bows, the dynamic duo will be transported to Victorian London for a special episode. BBC and PBS’ “Masterpiece” have yet to release an air date for the special, and season four is likely to air in early 2016.