"Beren and Lúthien" is a tale from J.R.R. Tolkien's legendarium, primarily found in "The Silmarillion." It tells the story of a mortal man, Beren, and an immortal elf maiden, Lúthien, who fall in love despite the challenges posed by their different natures. Their love leads them on a perilous quest to retrieve a Silmaril, a precious jewel, from the dark lord Morgoth. The narrative explores themes of love, sacrifice, and the struggle against evil. Lúthien uses her magical abilities to aid Beren in their quest, showcasing the power of love to overcome great obstacles. Their story has inspired many adaptations and remains a significant part of Tolkien's mythology.