It’s there that she meets Percy Shelley, with whom she’s instantly infatuated. Instead of the awkward man Percy was said to be in real life, and who Mary didn’t initially find appealing, Douglas Booth gives him the teen dream treatment.

But the appeal of the male characters is dampened as we learn more about them. Percy and Lord Byron are mostly chauvinists and womanizers, and sometimes downright boorish. Whether Lord Byron and Percy had all of the unsavory traits we see in the film is debatable, but there is still truth to the events of the film. 

Percy Shelley was married to a woman named Harriet at the time he met Mary. She knew of his marriage, but believed Harriet was beneath Shelley intellectually –– a woman concerned more with beauty than the politics and philosophy that stimulated Percy. In Mary he found an equal, someone with whom he could share his most unconventional ideas, namely his atheism and disdain for marital conventions. Mary was also no stranger to unconventional ideas. Her father believed marriage was stifling and her mother authored the controversial text, A Vindication of the Rights of Women, before her untimely death in 1797, just 12 days after the birth of her daughter. 

The film shows how these events lead to her writing an unusually dark book for a woman her age. But death is no stranger to Mary, beginning with her mother and then, most devastatingly, the child she has with Percy when she’s eighteen. The death of her daughter is followed by another event that strikes Mary to her core. When she visits a Phantasmagoria show with Percy and Claire, she’s intrigued when she’s introduced to the science of “galvanism,” the use of electricity to reanimate the dead.