The Party | Natasha Preston

In the heart of the English countryside, Bessie and her closest friends gather at a remote castle for a secret party destined to make this the best spring break ever.
But when one of them dies, the party takes a lethal turn .
.
.Trapped inside as a deadly storm rages, it soon becomes clear Bessie and her friends are being stalked by a killer.
As the body count rises, and secrets about the past unravel, Bessie begins to suspect that she doesn't know her friends quite as well as she thought.