Sasneham Sumithra is a murder investigation movie. Balan (Suresh Gopi)who is a Navy officer who falls in love and later marries Sumitra. Later he resigns and settles down with business, but Sumitra’s father and cousin do not like Balan. Under mysterious situations Sumitra commits suicide.
Balan once again gets married to Warrier’s only daughter Seetha (Ranjini). But when the well in Balan‘s house gets cleaned, a skeleton is found inside. The forensic reports confirms that it is Sumitra’s skeleton and that she was murdered. A police officer Muhammed Kutty (Lalu Alex) who comes to investigate the case and how he goes about it and traces the killer forms the rest of the story.