Sherlock (Robert Downey) deduces that Blackwoods (Mark Strong) final part of the ritual is to kill members of Parliament with a cyanide gas derived from pigs. Irene (Rachel McAdams) and Sherlock disable the gas device. Irene runs away with the gas cylinders and Sherlock runs after her. Blackwood, Sherlock and Irene meet at the Tower Bridge thats under construction. After a fight, Blackwood is caught on a rope tied to a heavy piece of metal. As Blackwood is slipping away, almost falling off the bridge, Sherlock debunks Blackwoods magic: 1) Blackwoods father was killed by a poisonous compound thats activated by water, bath powder and copper from the bath tub. The compound wasnt traced because the police drained the water from the tub. 2) The U.S. ambassador caught on fire by a combination of a substance on his clothes and a spark from firing his gun. 3) those who were on Blackwoods side wouldnt have suffered if the gas had been released in Parliament because they drank the antidote on the night that the ambassador died. 4) Blackwoods tomb wasnt destroyed from the inside.. it was shattered in pieces, glued together and shattered again. Holmes figured this out by examining the ingredients of the dwarfs experiments and the tomb. After the explanations, a piece of the bridge falls down causing Blackwood to fall and become entangled in chains and hang to his death. Irene reveals to Holmes that the mysterious figure who ordered her to hire Holmes is Professor Moriarty. She warns Holmes to be careful because hes very wicked and very brilliant. At his home, Sherlock explains to Watson (Jude Law) and Mary how Blackwood survived the gallows and faked his death: on the rope used in the execution there was a hidden hook that distributed Blackwoods weight to his waist so his neck wouldnt break. Blackwood faked his death with a substance made from rhododendron (another ingredient found in the dwarfs lab). Clarkie, a police officer, tells Holmes that a police officer has been killed by a shot to the head with a low caliber bullet and that part of the gas device is missing. Holmes deduces that it was Moriarty who killed the officer and that hes in possession of the remote control technology used for the gas device. When Irene was running away with the cylinders, that was a diversion, and Moriarty stole the remote control and parts of the device. Holmes takes the case and his future battle will be against Professor Moriarty...
