(writing this one out and posting it because bombing petratodd's box would be a huge and long ask *said the vicar to the showgirl*)
What no one expects in Season 4 is that little old ladies are getting kidnapped. There’s no real rhyme or reason, except that they’re all famous for some dish — kugel, dumplings, mince pies, chocolate cake — that sort of thing.
And Sherlock ignores it because Sherlock has other things to do like screech on his violin, drug John with some sort of hallucinogenic toad venom or annoy the piss out of Molly, because he can. Until Mrs. Hudson gets kidnapped.
Turns out she makes a killer brownie and not just the herbal soother kind of brownie, but a fantastic brownie where the edges are perfectly crisp, there’s the right balance of chocolate and flour so it’s not too fudgy, but also not too cakey.
So Sherlock goes ballistic. And is on the case. He solves it and learns the kidnapper is:
Turns out Mycroft has been kidnapping all the grandmas. Because he wants to learn how to cook their dishes, but they’re slowly driving him mad because their measurements aren’t precise at all.
"WHAT THE HELL IS A PINCH? AND HOW DO YOU MEASURE SUMMADIS AND SUMMADAT?"
"WHAT DO YOU MEAN, MIX UNTIL IT LOOKS RIGHT?"
"I DO NOT KNOW WHAT YOU MEAN WHEN THE BUBBLES ARE A CERTAIN WAY."