The Secret History by Donna Tart - "A Murder Mystery in Reverse"

This one is described as a Dark Literary Mystery Thriller... Wildly popular, and an interesting follow-up to contrast with our last read Station Eleven (which I think of as a somewhat optimistic post-apocalyptic tale about the unstoppable power of the creative spirit).

Here's the blurb for The Secret History:
Under the influence of their charismatic classics professor, a group of clever, eccentric misfits at an elite New England college discover a way of thinking and living that is a world away from the humdrum existence of their contemporaries. But when they go beyond the boundaries of normal morality they slip gradually from obsession to corruption and betrayal, and at last—inexorably—into evil.