This is a Malayalam language film and although from the horror genre, a true classic.
The film is led by Sathyan playing a difficult role with a shocking twist. But the show stealer and the main character is portrayed by Sharada. A true combination of beauty, sensuality and powerful performance was needed in this role, and Sharada meets all the parameters to the hilt. Although a winner of multiple National Awards (only exceeded perhaps by Shabana Azmi) one still feels she still didn't the level of fame for the amount of talent she portrayed in difficult roles like these.
The film is about a professor getting too engrossed in his work and falling to realise the difference between reality and hallucination. And how an inferiority complex can inhibit and even bring out the worst in you.
The ending sequence in the movie "Life of Pi" where the lead is asked to recount what happened, and this time "the truth" is a tribute to a similar sequence at the end of this film.
Highly recommended watch.