The Return of the King: Being the Third Part of the Lord of the Rings · Chapter 8
Denethor's Despair and Death
As Faramir lies wounded, Denethor's despair—fed by the palantír—drives him to attempt burning his son alive. Gandalf and Beregond intervene; Denethor sets himself alight with the Seeing-stone and perishes in the flames.
Outcome
Denethor dies; Faramir is saved; Aragorn's claim to kingship becomes clear as the Steward's line ends in tragedy.
