Neverworld Wake by Marisha Pessl. 2018 Hardcover (YA)

It's been one year since graduation, and Beatrice Hartley has mixed feelings about joining her friends for a weekend reunion.
She's right to be worried. After a night out, they narrowly avoid a collision with a car on a deserted road. Or so they believe.
Back at the mansion where they are staying, a mysterious man knocks on the door during a raging storm. He tells them that they must make a choice: one of them will live, and the rest will die. And the decision must be unanimous.
Soon time backbends. Beatrice and her friends are forced to repeat that dreadful day so many times they lose count. With each replay, events twist and fears come alive in horrifying ways.
This nightmare, this nothingness . . . this is the Neverworld Wake.
To escape, they have to vote. But how do you choose who to kill? And then how do you live with yourself?