So, this one is a bit of a stretch, I admit. I landed on Electric Company, which meant that I needed to read a book with a character in STEM - science, technology, engineering and medicine. I restarted the Mary Russell series after finishing The Murder of Mary Russell, and decided that I could reasonably shoehorn this one into that category. Mary Russell is a student at Oxford University in the disciplines of theology and chemistry, Sherlock Holmes himself is constantly conducting scientific experiments, and Dr. Watson is a doctor. There you have it - 3 characters in STEM.
This one is a favorite in the series. I really like Veronica Beaconsfield, and enjoyed going on a shopping spree with Mary now that she has reached her majority and gotten her inheritance.