Mary Shelley's 'Frankenstein' was published when she was 20 years old, but it is more than just a precocious book of early science fiction. In Episode 3 of The Book Club, Amit Varma explains how Shelley fearlessly tackled big themes, and delved as deep into human nature as the best literature of the time. Her book gave birth to many tropes that still exist – and showed an ambition that has since characterised the best writing in a genre she helped create.