Mélisande is lost and weeping in the forest by a spring when Golaud, who is hunting and also lost, finds her. Although she resists Golaud's attempts to touch her and comfort her, they leave the forest together, and she becomes his wife. After attaining, with the help of his half-brother Pelléas, his grandfather's forgiveness for not marrying the woman chosen for him, he brings Mélisande to the family castle, a gloomy place with the stench of death thought to be seeping from a subterranean lake beneath the castle.
Mélisande is made sorrowful by the castle but finds cheer in the walks Pelléas takes her on in the woods. By Blind Man’s Spring, Pelléas questions her about her first introduction to Golaud, at which she drops her wedding ring into the spring. Pelléas and Mélisande come to love each other--although to her dying breath she claims innocence--kissing each other passionately when they are caught together by Golaud one dark night.
Golaud slays Pelléas and chases Mélisande into the forest, wounding her slightly. He carries her limp body back to the castle where she gives birth prematurely to a tiny baby daughter. Still claiming her innocence in her love for Pelléas as Golaud questions her, she dies with the words of the physician echoing through the room in which he said that, having been born without reason to die, she was now dying without reason.