Trama

Detective Sherlock Holmes and his stalwart partner Watson engage in a battle of wits and brawn with a nemesis whose plot is a threat to all of England.

After finally catching serial killer and occult "sorcerer" Lord Blackwood, legendary sleuth Sherlock Holmes and his assistant Dr. Watson can close yet another successful case. But when Blackwood mysteriously returns from the grave and resumes his killing spree, Holmes must take up the hunt once again. Contending with his partner's new fiancée and the dimwitted head of Scotland Yard, the dauntless detective must unravel the clues that will lead him into a twisted web of murder, deceit, and black magic - and the deadly embrace of temptress Irene Adler.—The Massie Twins

In London, Sherlock Holmes and his partner Dr. John Watson captures the follower of black magic and serial killer Lord Blackwood that has already killed five women when he is near to kill his sixth victim. Blackwood is sentenced to be strung up and Dr. Watson attests his death. However, Blackwood mysteriously returns from the afterlife and Inspector Lestrade summons Sherlock Holmes to help the Scotland Yard in the investigation. Meanwhile Dr. Watson intends to get married of the gorgeous Mary Morstan while Sherlock is visited by his former lover Irene Adler that has a secret agenda.—Claudio Carvalho, Rio de Janeiro, Brazil

With the arrest of Lord Blackwood, Sherlock Holmes and Dr. John Watson believe they have stopped one of London's most dangerous killers, responsible for five deaths and about to commit a sixth when he is apprehended. Several months later he is hanged for his crimes but rumors begin to circulate that he is in fact still alive, having used managed and the black arts to escape society's judgment. When they disinter his remains, they find the body of another man in the coffin. Soon, all of London is atwitter with the news that Blackwood has risen from the dead and for some, he is the devil incarnate. With the assistance of the very capable Irene Adler, Holmes and Watson must stop Blackwood before he can initiate his master plan: the takeover of the British government and eventually, world domination.—garykmcd

As a spate of ritualistic murders terrorises late-1800s Victorian London, the lithe pugilist and debauched detective with the uncanny sense of deduction, Sherlock Holmes, and his acutely observant brother-in-arms, Dr Watson, manage to send to the gallows their occultist arch-enemy, Lord Blackwood. However, evil knows no boundaries--and as the disquieting rumours that the fiendish practitioner of the black arts has eluded death start to spread like wildfire--a mysterious copycat picks up where the deceased aristocrat left off. Now, against the backdrop of rampant superstition, Sherlock's feisty old flame with a hidden agenda, Irene Adler, has returned to further complicate matters, as the seemingly resurrected Blackwood continues his reign of terror. Has the dark lord, indeed, returned from the dead? Is he intent on slaughter and destruction?—Nick Riganas

In 1890 London, private detective Sherlock Holmes (Robert Downey Jr.) a bohemian scientist and eccentric detective-for-hire and his partner Dr. John Watson (Jude Law) Holmes' close friend who is also a surgeon and a veteran of the Second Afghan War, prevent the ritualistic murder of a woman by Lord Henry Blackwood (Mark Strong). Blackwood is an aristocratic serial killer dabbling in the occult to compel others to do his bidding. Blackwood has killed five other young women in a similar manner.

Inspector Lestrade (Eddie Marsan) and the police arrest Blackwood. Three months later, Watson is engaged to Mary Morstan (Kelly Reilly) a governess whom Watson wishes to marry, causing a conflict with Holmes. Watson invites Holmes for dinner with Mary and she slaps her when Holmes deduces wrongly that Mary is a gold-digger. He infers that Mary left her previous fiance to come to England for better prospects. But in fact, Mary's ex had died. Watson is moving out of 221B Baker Street; while he enjoys their adventures together, Watson looks forward to not having to deal with Holmes' eccentricities.

Meanwhile, Blackwood, who claims to have supernatural powers, has been sentenced to death and requests to see Holmes, warning him of three more unstoppable deaths that will cause great changes to the world. Blackwood is subsequently hanged. Watson is the attending physician and pronounces him dead.

Holmes is visited by Irene Adler (Rachel McAdams) an American Femme Fatale from New Jersey who outwitted Holmes twice. Irene is a former adversary who asks him to find a missing man named Luke Reordan. After her departure, Holmes follows her as she meets with her secret employer, and only learns that the man is a professor and that he intimidates Adler.

Meanwhile, sightings of a living Blackwood and the discovery of his empty tomb convince the authorities that Blackwood has risen from his grave. Reordan is found dead inside Blackwood's coffin. Following a series of clues from the body, Holmes and Watson find Reordan's hideout. They track his address via the articles recovered from his person and discover experiments attempting to merge science with magic.

After they survive a battle with Blackwood's men when they try to torch the lab, Holmes are Watson are arrested by the police. Watson is bailed out by Mary. Holmes is taken to the Temple of the Four Orders, a secret magical fraternity with considerable political influence. The leaders are Lord Chief Justice Sir Thomas Rotheram (James Fox), U.S. Ambassador Standish (William Hope), and Home Secretary Lord Coward (Hans Matheson). Unknown to anyone Home Secretary is Blackwood's right-hand man and assisted Blackwood in all his murders and was one of the few of his allies aware of Blackwood's usage of technology to feign magical powers.

The leaders ask Holmes to stop Blackwood, a former member of the society and Sir Thomas's secret illegitimate son. Thomas tells Holmes that Blackwood was conceived during one of the rituals of the Order. Blackwood has been murdering many women to enhance his powers. They hand him a book of spells and tell Holmes that Blackwood is trying to raise an army that will alter the course of history.

Holmes meets Irene and tells her that Reordan is dead and asks her to leave town asap. That night, Sir Thomas drowns in his bath as Blackwood watches, and the next night Lord Coward calls a meeting of the Order. He nominates Blackwood to take command in place of Sir Thomas and Blackwood reveals himself to the group, explaining his intention to gain control of the United States. Standish attempts to shoot Blackwood but bursts into flames when he pulls the trigger of his gun, falling out a window to his death.

Holmes and Watson find the body of their assailant from Reordan's house and deduce that he has been in a factory or a butchery near the river. They get to the factory and find that a machine has been recently removed from there. Blackwood teases them and then dangles Adler moving in a path towards a meat cooking flame. Holmes and Watson get busy trying to save her from certain death. They manage to save her from the flames and then a butchering saw. Blackwood leaves, but blows up the factory, which also the trio survive somehow.

Adler tries to leave London, but her mysterious employer asks her to get the machine that Reordan was making for Blackwood, else he will kill Holmes.

Lord Coward (who controls the police) issues an arrest warrant for Holmes, causing him to go into hiding. Holmes studies the rituals of the Order and recognizes their symbols in Blackwood's staging of the murders; from this, he deduces that the targets of the final murder are every elected member of Parliament. With the aid of Lestrade, Holmes fakes his arrest and is taken to see Coward, where he uses evidence on Coward's clothes to deduce Blackwood has conducted a ceremony in the sewers beneath the Palace of Westminster. Holmes escapes from Coward's window and into the Thames, where Watson is waiting for him.

Holmes escapes and he, Watson, and Adler find Blackwood's men in the sewers guarding a device based on Reordan's experiments, designed to release cyanide gas into the Parliament chambers and kill all but Blackwood's supporters, to whom he has secretly given an antidote. Blackwood comes before Parliament and announces their impending deaths, then attempts to activate the cyanide device by remote control; Adler is able to deactivate it with a controlled explosion.

Blackwood flees Parliament and sees Holmes chasing Adler, who has taken canisters of cyanide from the device, through the sewers, and pursues both to the top of the incomplete Tower Bridge. Blackwood subdues Adler and fights Holmes, as the latter deduces how all of Blackwood's supposed supernatural feats were the work of science and trickery. He survived the hanging by using a system of hooks and belts to distribute his weight around his waist and keeping his neck intact, The tombstone was broken prior to his burial and put together with an ancient adhesive of honey and milk, Thomas was paralyzed by a chemical agent activated by mix of copper and water, Standish was killed by a flammable liquid compound that was poured on him in what looked like rain. Blackwood plummets off the bridge and falls entangled in a noose of chains, the chain wrapping around his neck hanging him for good.

Adler explains to Holmes that her employer is Professor Moriarty, and she warns that Moriarty is not to be underestimated. As Watson moves out of 221B, the police report to him and Holmes that a dead officer was found near Blackwood's device. Moriarty used the confrontations with Adler and Blackwood as a diversion while he took a key component, based on the infant science of radio, from the machine. Holmes looks forward to the new case and his new adversary.