WARNING: This article contains spoilers from Season 3 of Sherock.

One of the biggest surprises leading into the new season of Sherlock came at the very end of season 3's finale: Moriarty's appearance. The show's creators, Steven Moffat and Mark Gatiss, won't reveal the meaning of the ending, of course, despite everyone's attempts to find out.

Moffat is on record as saying, "I can't really say what we're doing with that, but there is no last-minute whim in this. We've had what we're going to do with Moriarty in place from before the second season. Exactly what we're going to do. I remember talking it through with Andrew Scott, who plays Moriarty. Wait and see what's going to happen," when he was asked if Moriarty's appearance at the end is a big plot point or just something to mess with people.

All we can presume is that Moriarty will somehow have a major role in season 4.

Another interesting development is the emergence of female character roles, something to which the directors have previously alluded, specifically Molly.

"She's developed hugely," Moffat says. "She wasn't even meant to come back after her first appearance, but she worked so well. Louise Brealey was so good. The girl with the unrequited crush became the first person to make Sherlock apologize in 'A Scandal in Belgravia,' and then you see it really shift around. Whereas all of Sherlock's emotion on the rooftop when he's talking to John in 'The Reichenbach Fall' is completely faked -- he's just trying to give his friend a bad time so he'll be in an emotional state to believe what's about to happen -- the emotion when Sherlock turns up to Molly in that episode and says 'I need you,' I mean, it's amazing everyone didn't just get it right there."

If you haven't seen all the season 3 episodes yet, you have time to catch up before the season 4 release date.