The Lord of the Rings - Fellowship of the Ring's opening scene

The prologue, spoken by Galadriel, shows the Dark Lord Sauron forging the One Ring which he can use to conquer the lands of Middle-earth through his enslavement of the bearers of the Rings of Power—powerful magical rings given to individuals from the races of Elves, Dwarves and Men. A Last Alliance of Elves and Men is formed to counter Sauron and his forces at the foot of Mount Doom, but Sauron himself appears to kill Elendil, the king of the Mannish kingdom of Gondor. Just afterward, Isildur grabs his father's broken sword Narsil, and slashes at Sauron's hand. The stroke cuts off Sauron's fingers, separating him from the Ring and vanquishing his army. However, because Sauron's life is bound in the Ring, he is not completely defeated until the Ring itself is destroyed. Isildur takes the Ring and succumbs to its temptation, refusing to destroy it, but he is later ambushed and killed by orcs and the Ring is lost in the river into which Isildur fell.

The Ring is found two-and-a-half millennia later, and eventually it comes to the creature Gollum, who takes it underground for five centuries, giving Gollum "unnaturally long life." The Ring leaves him however, and is found by the hobbit Bilbo Baggins, much to the grief of Gollum. Bilbo returns to his home in the Shire with the Ring.