El romance entre el poeta Percy Shelley y la por entonces adolescente Mary Wollstonecraft Godwin, que la inspiró para escribir Frankenstein.
 | Elle Fanning | Mary Shelley |
 | Douglas Booth | Percy Shelley |
| Maisie Williams | Isabel Baxter |
| Joanne Froggatt | Mary Jane Clairmont |
| Bel Powley | Claire Clairmont |
 | Stephen Dillane | William Godwin |
| Ben Hardy | John Polidori |
| Tom Sturridge | Lord Byron |
| Hugh O'Conor | Samuel Taylor Coleridge |
| Ciara Charteris | Harriet Shelley |
| Jack Hickey | Thomas Hogg |
| Sarah Lamesch | Eliza |
| Donna Marie Sludds | |
| Laurence Foster | Bookseller |
| Michael Cloke |
