YA + murder mystery = fast-paced plots without a bunch of existential fluff. We bit off our fingernails reading these books & series, even if they don't ACTUALLY start with a body.
This oldie was a perennial favorite in my school library, and it features one of the best opening paragraphs in the world.
Cadence is one of the cousins in a perfect, wealthy family who is clearly hiding something weird this summer on their annual trip. Check out the equally good but very different prequel, Family of Liars, too.