Arcadia Summary

In a historic country house in Derbyshire, England, a lively thirteen-year-old student named Thomasina Coverly engages in conversation with her twenty-two-year-old tutor, Septimus Hodge. The young girl's curiosity is evident as she poses thought-provoking questions concerning the concept of "carnal embrace" and the principle of reversing motion. The narrative is momentarily interrupted when Jellaby, the butler, delivers a letter to Septimus from Mr. Chater. The peaceful environment is disrupted as Lady Croom, the estate's mistress, expresses her discontent with Noakes's modern plans to remodel the lush and scenic surroundings of their residence, Sidley Park.

Fast forward to the present, the story takes place in the same location, and new characters are introduced - Hannah, Chloe, and Bernard. Hannah is trying to gather details about the Sidley Hermit, while Bernard seeks information about Ezra Chater. Bernard unveils an intriguing theory, concluding from some documents he discovered, that Lord Byron was involved in a fatal duel with Chater, which was ignited by a romantic affair with Chater's wife. The implication is that the scandal prompted Lord Byron's hasty departure to the US.

Alternating between the two timelines, Thomasina expresses her aspiration to devise equations that reflect nature, challenging conventional mathematical forms. The narrative also reveals Mr. Chater's resentment towards Septimus over a romantic entanglement. The present-day narrative unveils Thomasina's advanced mathematical work, which impresses Valentine, and Bernard rehearses his scandalous theory. The narrative climaxes with the revelation that Chater was actually killed by a monkey bite, debunking Bernard's premise. The story concludes on the eve of Thomasina's seventeenth birthday, as she persuades Septimus into a waltz. Their dance continues, despite an interruption for a passionate kiss. The narrative ends with the presentation of a picture that confirms Septimus's identity as the hermit, and another dance begins, this time between Gus and Hannah.