Back in Mordor, Sam manages to free Frodo. Frodo demands the Ring, and Sam gives it to him. Dressed in Orc clothes they make their way to Mount Doom. They meet some Orcs, but because of their disguises, they get away.
Frodo becomes more and more tired as he gets closer to the mountain. Sam eventually has to carry him. When they are near the top, Gollum suddenly attacks them, desperate for the Ring.
What happens next? I'm afraid you'll have to read the books to find out. It's not what you expect!