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 aid of a nameless hunchback (Daniel Radcliffe) enslaved by the circus’ ringleader, and 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 develops a harness to improve his posture, and then names him “Igor Straussman” after a recently deceased roommate. 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.
After Igor suggests they use electricity to animate their creations, Victor procures parts from dead animals and creates a monstrous chimpanzee-esque 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 of their experiment, which goes awry when Gordon escapes and wreaks havoc through the university before being killed by Victor and Igor. 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.