Sherlock: 10 Most Outrageous Fan Theories

5. Baby Watson Will Die

At the end of series three, the Watsons are expecting a little girl (who they will not be calling Sherlock). But surely Sherlock and John's partnership - and therefore the show - is properly over if he has a child to look after? Unless...

Yes, fans fear Sherlock will go incredibly dark next series and that Baby Watson won't last long. The theory goes that the baby will die in the fourth series finale, at the hands of Moriarty who has actually had previous dealings with Mary (see more later). This would liken him to Rumpelstiltskin, the fairytale trickster who threatened to steal a woman's baby, which ties in to the many allusions to Grimm's fairy tales in The Reichenbach Fall.

This seems like an outrageous idea as, while it is often shocking, Sherlock has never been so nasty before. Yet Steven Moffat and Mark Gatiss have promised that the next series will be "dark." But they wouldn't really kill off the innocent child of our beloved John... would they?