5150 (2016) on Netflix

Plot summary

Autumn's stepsister is mentally unstable, and Autumn has her placed on a 5150, an involuntary mental-health hold. Her friends close ranks around her, and the stepsister is sent away. Two years later she resurfaces, vengeful, carrying secrets about all of them. Autumn and her friends are successful women, and the fame and the fortunes they enjoy rest on a secret they have kept. The stepsister blackmails them with what she knows about how they gained it all. To protect that secret, the women commit a horrific act.