Ok, I'll start this after the guy near to us fell asleep and started snoring in the cinema. It's not that bad a movie, maybe he was just tired.
So, Watson is pinned down by the Colonel, while Holmes is being tortured by Moriarty in the weapons factory. Holmes has been impaled on a great big metal hook, and is being pushed around while his enemy looks for answers. Moriarty needs to know who Watson sent the telegram message to about his plans.
Watson realises that he is behind a huge cannon. He takes aim at the Colonel in a brick tower overhanging the factory. The Colonel panics and tries to escape. Watson take aim for a good long time and fires - but still misses. The colonel survives, but the tower takes a pounding - it breaks apart and crashes through the roof of the factory.
Watson runs in to rescue Holmes from the rubble. They both get out, not much the worse for wear. Later, the Colonel gets inside to the same place and pulls out Moriarty, the easy target. I know, I know. Maybe Holmes had amnesia brought on by the flying bricks and mortar. And Watson was just stupid to forget to look for the other man and save everyone a lot of trouble.
The Colonel has rallied the troops and they give chase. Holmes is clearly feeling a lot better now. They fire a few rounds back - including hitting one of the evil twin foot soldiers in the chest. With the gypsies, they run for the nearest train as mortars fall around them. The Colonel is taking out the gypsies with some success. Finally they make it to the train - but Sherlock is overcome by pain and blood loss, falls unconscious and his heart stops. Watson cannot revive him - but then thinks to use the adrenaline syringe, and Holmes is fit and healthy again.
Now that Holmes knows the plans of Moriarty for world domination, they know where and when Rene the assassin will strike. They have seen the handiwork of Moriarty's evil doctors, so he will have been given a face transplant too.
They meet Mycroft in Switzerland, who tells them that the telegram wasn't successful as Moriarty has close ties with the Prime Minister. With Simza, they manage to enter the peace summit party and try to guess the identification of Rene. To keep Moriarty busy, Holmes invites him to the balcony for a friendly game of chess. Meanwhile Watson has an idea - that the only person in the room who will not respond to a sudden noise or explosion must be the one person expecting it - the murderer. He knocks over a waitor - and finds his man. Rene is acting as one of the foreign ambassadors. His sister jumps in the way to try and convince him to do the right thing, but he doesn't listen.
Watson tackles him and he is soon captured by the Swiss police and bundled outside, but the Colonel shoots him with a posion dart and he dies outside. He was the last remaining loose end, and Holmes responds to the noises outside - and knows he has no evidence now. But -- what about the Colonel? Isn't he a loose end?
Things move quickly now outside as Holmes and Moriarty continue their battle of wits, and chess. Holmes has his man - he realized some time ago that Moriarty always kept a small red book with him. While he was being tortured he swapped it for a copy, and sent it to Watson's wife with directions to hand it to the inept police inspector. The book contained details of Moriarty's accounts and assets - but it was in code. To decipher it he used the one book out of place in his office - the one about Horticulture. The police used the cipher to track Moriarty's accounts and gain all the evidence they need.
Holmes plans the fight they'll have, again, in slow motion - but he knows he will lose against the former boxing champ. Instead he hooks his leg, blows soot in his eyes and ... at that moment Watson walks out onto the balcony. Holmes falls backwards with Moriarty off the ledge and down into a giant waterfall.
Sometime later, at Baker Street, Watson has finished the story of Sherlock Holmes. His wife delivers a package - of the oxygen apparatus from before, which gets him thinking. As he chases after his wife to ask who delivered it, Holmes reveals himself in his camouflage suit where he has been sitting on a chair. No real reason for this, but nevermind. He walks up to the typewriter and adds a question mark ater the fnal sentence - "The End?"
Cue end credits, which actually look really good.