She attended Chapin School and Radcliffe College,[4] finishing her education at Countess Montgelas' in Munich, Germany.

[7] Through the couple's friendships in Paris, Theodora became connected with writers and editors for the Paris Review, including George Plimpton and Peter Matthiessen, co-founders of the Review; Scottish novelist Alexander Trocchi; the poet Christopher Logue; and Alabama poet and screenwriter Eugene Walter.

Like Highsmith, she created characters who seemed quite normal on the surface and in relation to the social conventions of their day, but who had another side to their lives and their identities.

[1] Indeed, her first novel, Meg, published in 1950, garnered a response from Highsmith, who notoriously rarely reviewed anything:[9] "She writes with a skill and command of her material that should set her promptly into the ranks of the finer young writers of today.

"[7] Also similar to Highsmith, Keogh's novels were also noteworthy for exploring gay and lesbian themes, which were daring topics for the era in which she was writing.

Second, she is admired for her exploration of psychological issues and in thus creating complex characters who often present one personality to the world while having a secret and immoral life that is in contradiction.

Explorations of the tensions between the socially accepted and the inwardly rebellious or evil side of the same person's psyche have made Keogh's novels of greater interest.

[7] Influenced by the Greta Garbo film Anna Christie, she bought a tugboat, which she sailed in the Atlantic Ocean.

During the marriage, the couple lived in an apartment at the Hotel Chelsea in New York, where she kept a margay, a South American tiger-cat similar to an ocelot, for company.

[12] Theodora moved to Caldwell County, in the western mountains of North Carolina where she became friends with the wife of Arthur Alfred Rauchfuss (1921–1989), owner of a chemical plant.

After his death, Keogh spent the last years of her life in North Carolina, in a house in the woods with cats and chickens.