You can stream or buy/download the movie legally in HD Hindi from these platforms (availability varies by region):

If you're looking for a gripping experience, the 2015 Bollywood film

Inspired by the infamous 2008 Noida double murder case (the Aarushi Talwar/Hemraj case), Rahasya follows the murder of 18-year-old Ayesha Mahajan, daughter of a prominent doctor. The prime suspects are her own parents, but CBI officer Sunil Paraskar (Kay Kay Menon) believes the truth is far more complicated.

The story reaches a climax during a stormy night when the true mastermind—the industrialist’s trusted lawyer—returns to the mansion to retrieve the last piece of incriminating evidence, leading to a high-stakes confrontation in the very room where the mystery began.