Frodo discovers Gandalf was delayed because the evil wizard Saruman imprisoned him until he escaped on the back of a giant eagle.
It is decided that the Ring must be destroyed at Mount Doom in Mordor, Sauron's home. Nine are chosen to do this - Frodo, Sam, Merry, Pippin, Gandalf, Strider (who is actually Aragorn, King of Men), Gimli (a dwarf), Legolas (an Elf), and Boromir, a man from Gondor.
They have to go through the mines of Moria, where Gandalf is killed by a Balrog. The survivors go to Lothlorien, where they rest for a while, and meet the Elf Queen Galdriel.
Boromir later tries to steal the Ring and Frodo runs off with Sam. The remaining friends are attacked by Saruman's Orcs, and Merry and Pippin are captured. Boromir is sorry and is killed trying to save them.