Death Note is based on a manga, which is so popular that it borne out several movies under its belt.
Death Note Movies (Review & Summary)
Death Note (2006)
Light is a genius law student. He hacked into the National Police network and found out that many murderers and criminals are getting away through lack of evidence.
He was so frustrated that he threw away his law book but at the same time found a black mysterious note book.
The note book has Death Note on its cover and it says that any human’s name entered into the note book will die. There are provisos of course to minimise mistake.
The writer must envisage the face of the person, before and while writing his name on the notebook. This is to prevent other people bearing the same name ending up dead.
The cause of death must be written immediately, within 40 seconds; otherwise the death will default to heart attack.
The Death Note book is actually a property of Ryuk, the god of death, who dropped it.
Ryuk found Light, who asked if Ryuk wanted the notebook back. Ryuk said that Light can pass it to anyone and Ryuk would then erase Light memory of the death note.
After Light was reassured that he will not have to surrender his soul to Ryuk, he decided to keep the Death Note but he was warned that he will suffer agony and fear from using the Death Note.
Light used the name Kira as the god of Justice.
The unexplained deaths of criminals have worried and intrigued the police. They are looking into this worldwide death with the help of an anonymous person, who comes by the name of L.
It would now be a battle of wits between Kira and L.
Light/Kira was an immature idealistic young man. He wanted to rid the world of criminals. He had gone beyond killing criminals. He had now started murdering those who thwart his vendettas against criminals. He just killed 12 FBI agents.