Inferno question

I am trying to find the title of a book I can only vaguely remember the plot of. I remember a few key points, however, as well as the cover (which is relatively similar to the cover of this topic’s context book, Inferno), and so I have listed everything I could recall about the book, in the hopes that someone knows what I’m talking about :)

Below is everything I can remember about the book
- It is set in a high school and has a female protagonist
- There was something odd about the school, with the headmaster or students
- It was a murder mystery novel, either the protagonist is investigating a murder or something of that sort is happening.
- The book has a red cover with a black tree on the front

If anyone recognises the book, please let me know :)
Thank you :)