Martin Freeman and Benedict Cumberbatch in last week's episode The Sign of ThreeBBC

Last night Sherlock came to a thrilling conclusion in one of the best episodes of the exhilarating BBC detective drama to date.

As we've come to expect from the show that left a nation wondering for two years just how Sherlock faked his own death, there was another twist and even more questions in need of answering.

Before we jump into all that however, first the need for a spoiler warning. A big spoiler warning, like this one...


How did Moriarty fake his own death?

His Last Vow's ending would have been a satisfying conclusion in its own right. Having shot a man dead, Sherlock was heading to eastern Europe on a mission for MI6 that he was unlikely to survive.

His brother Mycroft (who was given a long-overdue dose of humanity earlier in the episode) called back his brother only minutes into the flight due to a message appearing on television screens across the country.

"Did you miss me?"

Jim Morarity is back - so now, as in the two year build up to the third series, all the speculation will return to the rooftop of London's St Barts hospital. Only now the question is how Moriarty faked his own death, not how Sherlock did.

Will Steven Moffat and Mark Gatiss even bother explaining?

Episode one of this series offered two theories as to how Sherlock faked his death from the Holmes fan club and a proper explanation from the man himself.

Anderson, played by Jonathan Aris, saw holes in the version Holmes told him in person and found reason to not believe it. The idea from the writers was that no explanation would ever be satisfying enough for the hardcore fans.

Benedict Cumberbatch in Sherlock.BBC

So when series 4 airs, will they explain Moriarty's faked death or just let it slide? After all, what kind of explanation could there actually be – he did blow his own brains out mere inches from Sherlock's horrified face after all.

The two likeliest scenarios aren't exactly crowd-pleasers. First of all it could be that the Moriarty we thought we knew (played with wonderful madness by Andrew Scott) could have been a pawn of the real thing, and secondly there's the slim chance that it could have been a ploy of Sherlock's to ensure he never makes it to eastern Europe.

Scenario A may carry some weight as far as shock factor goes but it would disappoint fans of Scott and his performance. Scenario B is the most logical explanation, but also the one most likely to anger fans (and justifiably too).

Was this all planned since the series 2 finale?

Steven Moffat would like you to think it was, and could well say so in interviews, but I very much doubt it.

With Martin Freeman and Benedict Cumberbatch heading off to Hollywood back in 2012 the future of the series was in doubt – and in his apparent death Moffat and Gattis found a delightfully shocking way to despatch of Sherlock's number one foe and a fitting end for the character.

Lars Mikkelsen as Charles Augusts Magnussen.BBC

Will Sherlock killing a man be overlooked?

Sherlock Holmes is a murderer. Not just that but he killed one of the most powerful men in the western world when he shot Charles Augustus Magnussen in the head and freed those who he had blackmailed over the years.

He did it to free Watson and his troubled wife Mary from Mganusson's grasp, so forgiveness from them is a given, as I imagine it would be from many who found themselves under the thumb of Magnussen. But murder is still murder.

Many shows allow their characters to kill villains with very little consequence – but Sherlock has never been about that. Seeing Sherlock kill was a great move for the series, but for it to stick consequences of some kind will need to be shown.

What about this third Holmes sibling?

Hidden among the emotion and drama of Sherlock's apparent farewell to Watson was a seemingly innocuous line from Mycroft 'Don't Call Me Mike' Holmes.

Hopefully it won't be another two year wait until the show returnsBBC

While explaining how Sherlock couldn't be imprisoned for his crime a colleague of Mycroft's chimed in saying: "If this is some expression of familial sentiment..."

"Don't be absurd," shot back Sherlock's brother. "I am not given to outbursts of brotherly compassion... you know what happened to the other one."

So Sherlock and Mycroft have - or had - a brother (or possibly a sister). There's no way this was a throwaway line, so expect it to play a big part in the next series.

The issue of a third or fourth sibling has been a matter of debate for fans of the Arthur Conan Doyle stories for some time, one that it appears will be addressed in the next series, whenever it may air.

Last week Moffat confirmed that plans were already in place for series 4 and 5, and that the writing duo had even plotted out what will happen.