Nick Dear's adaptation of Frankenstein follows the story of Mary Shelley's novel from the perspective of Victor Frankenstein's creature. After he comes to life, the creature is cast out into the town of Ingolstadt, which he is then also cast out of because of his horrific appearance. He wanders through the countryside until he comes to the home of De Lacey, a blind man. The creature spends a whole year with De Lacey as he becomes educated while learning about the ways of man and how he was created. However, when De Lacey's son and daughter-in-law return to his home, they are horrified at the sight of the creature and force him out; the creature then retaliates by burning down their home.

The play then transitions to Geneva, where a young William Frankenstein is playing hide-and-seek with Elizabeth Lavenza, Victor Frankenstein's fiancée. The creature approaches William and, after confirming that he is near the home of his creator, murders him. The Frankenstein family discovers William's corpse in the river that night, along with some papers from Victor's old journal, which leads Victor to realize what has happened; he then heads towards the mountain to confront his creation. During this confrontation, the creature demands that Victor create a female creature, to which Victor agrees on the condition that the two will leave society and live in isolation. 

However, near the end of the female creature's creation, Victor has a dream about William, which leads him to abandon his plan and destroy his work on the female creature. Enraged, the creature nearly murders Victor and promises to take revenge on him. Victor, trusting that the creature will keep his promise of revenge, marries Elizabeth to lure the creature out of hiding so he can kill him; however, he is unable to do so, and the creature murders Elizabeth right in front of him. Victor is then blamed for Elizabeth's death and cast out of his home. With no other options on what he can do, Victor follows the creature north until the two have another confrontation, in which Victor nearly dies. The creature comments on how he does love his master, but the cruel treatment he received is what caused him to behave the way he did. The creature then taunts Victor to continue chasing after him, ending this classic story that deals with love and humanity.