Plot

Told from Igor's perspective, we see the troubled young assistant's dark origins, his redemptive friendship with the young medical student Viktor Von Frankenstein, and become eyewitnesses to the emergence of how Frankenstein became the man - and the legend - we know today.

James McAvoy and Daniel Radcliffe star in a dynamic and thrilling twist on a legendary tale. Radical scientist Victor Frankenstein (McAvoy) and his equally brilliant protégé Igor Strausman (Radcliffe) share a noble vision of aiding humanity through their groundbreaking research into immortality. But Victor's experiments go too far, and his obsession has horrifying consequences. Only Igor can bring his friend back from the brink of madness and save him from his monstrous creation.—20th Century Fox

As a grievous injury during a fateful performance leads to a brief but intense encounter between the deformed circus clown and amateur anatomist, Igor, and the ambitious medical student, Victor Frankenstein, soon, a mutually profitable partnership will form. Obsessed with the haunting mysteries of creation, the eccentric doctor works tirelessly on finding a way to overcome the obstacle of death by reanimating dead tissue through electricity and Igor's help; however, flawed early prototypes and an unwelcome brush with a resolute Scotland Yard detective threaten to put a premature end to the couple's efforts. In the end, just how far will Frankenstein go to create life out of death?—Nick Riganas

In London, ambitious medical student Victor Frankenstein attends a circus performance, where he helps save an injured aerialist, Lorelei, by aid of a nameless hunchback enslaved by the circus' ringleader, who harbors feelings for the girl. Impressed by the hunchback's vast knowledge of human anatomy, acquired from stolen books, Victor rescues him, drains the cyst on his back that causes his physical abnormality and gives him a harness to improve his posture - he then names him "Igor Straussman" after his roommate who is not often at home. The two then become partners in Victor's ongoing experiments to create life through artificial means, incurring the wrath of devoutly religious police inspector Roderick Turpin, who views their experiments as sinful..

In London, ambitious medical student Victor Frankenstein (James McAvoy) attends a circus performance, where he helps save an injured aerialist, Lorelei (Jessica Brown Findlay), by aiding a nameless hunchback (Daniel Radcliffe) enslaved by the circus' ringleader Barnaby (Daniel Mays), and who harbors feelings for the girl. The hunchback had been with the circus forever and was deployed as the resident clown in performances in front of live audience. The hunchback was not respected by anyone even in the circus, even though circuses thought of themselves as families. When the hunchback was not performing, he served as the company's doctor. He was fascinated by the topic of human anatomy. He wanted to know everything about the internal universe that made humans who they are.

Lorelei was performing on the swings without a net and came crashing down when one of the ropes broke. The hunchback arrives immediately for help and so does Victor. Lorelei had broken her collarbone and dislocated her shoulder. This was putting pressure on her lungs and hence she could not breathe. The hunchback uses Victor's pocket watch to fix Lorelei's collarbone and helps her to breathe.

Victor comments that the hunchback is wasted in the circus as he is a perfectly trained physician. Victor asks hunchback to join him at the hospital, which is overheard by Barnaby. Barnaby is livid and sets fire to all of hunchback's books and locks him in a case.

Impressed by the hunchback's vast knowledge of human anatomy, acquired from stolen books, Victor rescues him from his cage. Barnaby declares that the hunchback is a thief who stole from the circus and puts every performer I his path to escape. Victor helps the hunchback defeat the other performers, and together they make their way out of the circus, to freedom.

Victor realizes that the hunchback only has a fluid pocket, an abscess on his back, which causes him walk like a hunchback. The cyst had gone untreated for 18 years. Victor drains the cyst on his back that causes his physical abnormality and develops a harness to improve his posture and then names him "Igor" after a recently deceased roommate. Igor takes a bath in hot water for the first time and starts to look and feel like a human being, as years of accumulated grit and grime is washed off.

As Victor goes to teach his classes, it leaves Igor alone at home. Igor decides to venture out into the city. Igor visits the hospital where Lorelei is being treated and gives instructions to the nursing staff for specific medicines to be administered to Lorelei. Igor finds that he and Victor have become outlaws as their wanted posters are pasted all over the city.

The two then become partners in Victor's ongoing experiments to create life through artificial means, incurring the wrath of religious police inspector Roderick Turpin (Andrew Scott), who views their experiments as sinful. Turpin was told by Barnaby that the hunchback had stolen the contents of his safe and murdered a circus performer while escaping. Turpin believed that Barnaby was mistreating the hunchback, who tried to escape captivity.

After Igor suggests they use electricity to animate their creations, Victor procures parts from dead animals and creates a monstrous chimpanzee-like creature nicknamed "Gordon". Meanwhile, Igor reunites with Lorelei, now masquerading as the mistress of a closeted homosexual baron, and the two develop an affair, upsetting Victor, who views Lorelei as a distraction. Igor invites Lorelei to a demonstration on their experiment, which goes awry when Gordon escapes and wreaks havoc through the university before being killed by Victor and Igor. Victor and Igor manage to kill the creature, but the fallout causes Victor's expulsion.

Lorelei is horrified by Victor's experiments and urges Igor to dissuade him from pursuing the matter further, but Igor is reluctant to do so upon learning that Victor is driven by the need to atone for his indirect role in the death of his older brother, Henry, for which Victor's domineering father, Mr. Frankenstein (Charles Dance), blames Victor.

Victor is expelled from college for his unorthodox methods, and later approached by his wealthy, arrogant classmate Finnegan (Freddie Fox), who wants him to create a artificial humanoid creature. Victor and Igor outline a behemoth being known as "Prometheus", but Igor's deepening relationship with Lorelei soon causes a rift between them.

Shortly afterwards, Turpin and his men raid Victor's laboratory, hellbent on destroying his inventions, and during an altercation with Victor, Turpin loses both a hand and one of his eyes, while Victor and Igor are extracted by Finnegan's men and taken to his family's estate in Scotland, where Finnegan provides them with the necessary funds to build Prometheus. Igor is mistrustful of Finnegan and leaves after having a falling out with Victor. Finnegan later kidnaps and binds him, revealing his plans to kill Victor once Prometheus is complete and Weaponize his creation. Igor is then thrown into the River Thames to drown, but manages to escape and reunites with Lorelei, who nurses him back to health.

Once recovered, Igor returns to Finnegan's estate with Lorelei in tow in order to rescue Victor, and finds Victor on the verge of using lightning to animate Prometheus. He ignores Igor's pleas not to and activates the machine. Due to a power surge the machinery overloads however, killing Finnegan. After the ensuing chaos Turpin unexpectedly arrives, blaming and threatening Victor for his creation, upon which both realize the experiment was a success and Prometheus came to life. Victor shares a brief moment with Prometheus but is interrupted when Turpin opens fire on Prometheus, who eventually kills Turpin. Realising his efforts were misguided Victor joins forces with Igor to kill Prometheus by stabbing its two hearts.

After regaining consciousness the next morning, Igor reunites with Lorelei, who hands him a letter written to him by Victor, in which Victor apologizes for all the suffering he caused and recognizes Igor was his "greatest creation". Victor retreats to the Scottish countryside in search of new discoveries. He hints at continuing his scientific work and suggests they may one day meet again.