Sherlock (Benedict Cumberbatch) är inte på sitt bästa humör. Hans ärkefiende och egentligen riktiga utmaning, James Moriarty, är död och Sherlock sitter nu med, i hans ögon, undermåliga fall och klienter. Klienten Mr. Kingsley (Neal Barry) har sökt Sherlocks hjälp och får ett svar på sin fråga. Men när han insinuerar att Sherlocks slutledningsförmåga inte var så klockren som han hade trott tar det hus i helvete och Sherlock kör därpå över Mr. Kingsley, så att säga:
Mr Kingsley: "I... I thought you'd done something clever. Ah, now, but now you've explained it, it's dead simple, innit?"
Sherlock: "I withheld this information from you until now, Mr Kingsley, but I think it's time you knew the truth."
Mr Kingsley: "What do you mean?"
Sherlock: "Have you ever wondered if your wife was a little bit out of your league?"
Mr Kingsley: "Well..."
Sherlock: "You thought she was having an affair. I'm afraid it's far worse than that. Your wife is a spy."
Mr Kingsley: "What?"
Sherlock: "Her real name is Greta Bengtsdotter, Swedish by birth and probably the most dangerous spy in the world. She's been operating deep undercover for the past 4 years now as your wife for one reason only, to get near the American Embassy, which is across the road from your flat. Tomorrow the US President will be at the Embassy, as part of a official state visit. As the President greet members of staff, Greta Bengtsdotter, disguised as a 22 stone cleaner will inject the President in the back of the neck with a dangerous new drug, hidden inside a secret compartment inside her padded armpit. This drug will then render the president entirely susceptible to will of their new master, no other than James Moriarty."
Mr Kingsley: "What?"
Sherlock: "Moriarty will then use the president as a pawn to disstabilize the United Nations general assembly, which is due to vote on a nuclear non-proliferation treaty, tipping the balance in favor for a first strike policy against Russia. This chain of events will then prove unstoppable, thus precipitating World War III."
Watson: "Are you serious?"
Sherlock: "Of course not. His wife left him because his breath stinks and he likes to wear her lingerie."
Mr Kingsley: "I don't... Just the bras."