Hannah is already well-established as a researcher at the modern-day Sidley Park when we first see her.
Her first action in the play is to look through some garden books, pick up a theodolite, and head out into the garden.
Hannah re-enters the room and addresses Bernard Nightingale as Mr. Peacock, thanks to Chloë's lie of an introduction.
Hannah takes off her shoes because they are muddy from the garden, but Bernard's long-windedness makes her to threaten to put them on again just so she can kick him in the balls.
Hannah tells Bernard why she's suspicious of him: she's just written a book about a forgotten female author that the male academic establishment have made a sport out of mocking – especially a certain Mr. Bernard Nightingale.
Hannah tells Bernard some of what he wants to know (he's told her he's tracking down information on the poet Ezra Chater), and also describes her own project: taking the Sidley Park garden and its hermit as a starting point for discussing the cultural shift from Enlightenment to Romanticism.
When Chloë accidentally reveals Bernard's real name, Hannah is pissed off.
A prickly Hannah listens to what Bernard really wants to know (did Byron kill Chater in a duel?!), but refuses to let him horn in on her turf.
Hannah does, however, let Bernard know that Septimus and Byron went to school together, which excites Bernard into a frenzy that even Hannah's Arctic coldness can't freeze him out of.
After Bernard leaves, Chloë tries to set Hannah up with him, but Hannah is having none of it.
Hannah also thinks the crush that Chloë's silent brother Gus has on her is a joke – but just then, Gus comes in and sweetly gives her an apple.
Later, Hannah looks through some of Thomasina's old math books that Bernard has turned up in a cupboard, and tries to make sense of them with Valentine.
Bernard comes in with a new discovery – a book by Byron from the house library with an added handwritten stanza – but Hannah is not impressed.
After Bernard goes off on another mad tangent, Hannah returns to her conversation with Valentine, who tells her that you'd have to be crazy to do the kind of math Thomasina seems to be writing about without a computer.
This statement sends Hannah back to the description of the crazy Sidley Park hermit.
Later, Hannah interrupts Bernard's lecture describing his Byron discoveries with a new find of her own, a letter which she wants to show Valentine.
Hannah promises, at Chloë's insistence, to listen quietly to Bernard's speech, but his out-there claims are too much for her to take in silence.
Hannah tries to convince Bernard that he shouldn't go public till he's more certain that his theories will hold water, but once he trashes her book (again) she washes her hands of him.
What really chaps Hannah's hide, however, is Bernard's claim that the picture on her book's cover is not actually Byron and Caroline Lamb – she knows it's them.
Hannah refuses Bernard's invitation for her to come to London and have sex with him.
After Bernard leaves the room, Hannah finally gets to show Valentine her letter, but it's still not conclusive enough to prove her theory that Thomasina was making important new mathematical discoveries.
Later, Hannah meets up with Valentine again, and they talk about the media coverage Bernard's been getting.
Valentine flirts with Hannah, though it's unclear how serious he's actually being.
Valentine shows Hannah "the Coverly set," graphs of Thomasina's equations extended by computer, and Hannah exclaims at how beautiful they are.
Hannah talks about Thomasina's fate: she died in a fire the night before her seventeenth birthday.
Hannah persists in believing that either Thomasina or Septimus was an undiscovered mathematical genius. Valentine insists that it's impossible for them to have gone beyond their historical limitations.
Hannah, reading Thomasina's mother's garden journals, comes across conclusive evidence that the Ezra Chater who Bernard is so certain Byron killed actually died of a monkey bite on a botanical expedition.
Hannah wastes no time in sharing this information with Bernard, and tells him that she plans to write a letter to the Times to make sure everyone else knows, too.
Valentine explains to Hannah the meaning of Thomasina's mysterious diagram – it has to do with heat exchange.
Hannah witnesses Bernard's rude departure from Sidley Park.
Hannah and Gus waltz together awkwardly as the play ends.