10 MORE Horror Movies That Go Totally Insane At The End

5. A Cure For Wellness

A Cure for Wellness is one of the most underrated horror films of the 21st century, as well as arguably one of the best movies out there to have a rotten score on Rotten Tomatoes. This begins with American businessman Lockhart (Dane DeHaan) going to retrieve his CEO from a sinister wellness clinic in the Swiss Alps, and by the end, this gloriously bonkers excursion into the fantastic goes far beyond what anyone will have been expecting. 

It turns out that Dr. Volmer (Jason Isaacs), the man who runs the clinic, is a 200-year-old Baron who's been given an unnaturally long life, as the water from the local aquifer possesses supernatural properties. He's been conducting deranged experiments on his patients in order to create a life-giving essence.

Wait, there's more...

It also turns out that Hannah, a young woman who's been at the spa all her life, is the Baron's daughter, and as he was always obsessed with having a pure bloodline, he marries and assaults his own daughter once she comes of age. 

Granted, the movie is filled with surreal happenings - many of which involve eels that Volmer uses in his experiments - from start to finish, but it goes particularly hard by the end. Still, it does end happily, as Lockhart and Hannah escape, with the former quitting his soul-destroying corporate job, and Volmer is eaten alive by his own eels. Poetic justice.