Inspector Persis Wadia is the first female inspector in the newly formed Indian Republic. She, and a bunch of other police, have been relegated to the Malabar House– Persia because she is a woman, others because they made important mistakes or were too chummy with the colonizers. And Malabar House gets the trickiest cases– mostly those with political ramifications.
In The Dying Day, Persis is called in after a 14 c edition of The Divine Comedy is stolen. The mild-mannered British scholar who was working on it disappears at the same time, and then riddles and ciphers start appearing.