(Spoiler alert) Sherlock fans have been left with another cliff-hanger on their hands after the series finale His Last Vow aired on Sunday night.

The episode saw viewers faced with a complex plot as Sherlock (Benedict Cumberbatch) took on the villainous Charles Augustus Magnusson one last time.

Meanwhile Watson’s new wife Mary (Amanda Abbington) revealed that she was not as innocent as she first seemed, ultimately putting the detective’s life in danger.

However the biggest twist of all was left for the last five minutes as Sherlock boarded a plane and the end credits appeared to begin rolling.

Although things looked to be wrapped up the titles promptly faded to reveal the detective’s arch nemesis Moriarty (Andrew Scott) asking “Did you miss me?”

The twist is likely to leave fans of the show questioning how the villain survived his apparent suicide at the end of series two, in the same way as they were left wondering how Sherlock survived his rooftop plunge in that season’s finale The Reichenbach Fall.

That question remained unanswered when the show returned on New Year’s Day with series three opener The Empty Hearse.

Co-creator Steven Moffat recently confirmed that Sherlock will return for a fourth and fifth series.