The Sanatorium (UK)

A beautiful, eerie hotel in the Swiss Alps, recently converted from an abandoned sanatorium, is the last place Detective Elin Warner wants to be. But her estranged brother has invited her there for his engagement party, and she feels she has no choice but to accept.

Arriving in the midst of a threatening storm, Elin immediately feels on edge. And things only get worse when they wake the next morning to find her brother's fiancée is missing. With access to the hotel cut off, the guests begin to panic.