Sam folds up his orc cloak and puts it under Frodo's head. Then he covers both of them in his Lothlórien cloak.
Sam gives Frodo water. When Frodo wakes up, Sam makes him eat a wafer of lembas.
They sleep for as long as they can, and when dawn comes, they see smoke pouring from Mount Doom.
That's the moment: Sam finally realizes that they will not return from Mordor.
For one thing, they have no food for the return journey.
He recognizes that the job he came to do is "to help Mr. Frodo to the last step and then die with him" (6.3.5).
Still, he wishes that he could see the Shire and his sweetheart, Rosie Cotton, and his family again before he goes.
As Sam surveys the landscape, he notices that the plains of Gorgoroth are actually filled with holes. That means they'll have a ton of cover, which is awesome, but it will be slow-going, which is not so awesome.
But there's nowhere to go but forward, so Frodo and Sam set out again, "crawling from hollow to hollow" (6.3.10).
Frodo's strength is failing quickly.
They don't meet any enemies during the day, though at night they hear the sounds of many feet marching past.
What makes this journey unbearable is the unrelenting pressure of the Power that is waiting for them.
Four days after their escape from the Tower of Cirith Ungol, Frodo trudges along without saying a word.
Sam watches him, desperate with worry.
They still have a day to go, they have only half a bottle of water left, and there is no hope of finding any more.
The night passes slowly and dawn comes, so Sam rouses Frodo for a final push.
Frodo pleads, "I can't manage it, Sam [...] It is such a weight to carry, such a weight" (6.3.22).
Sam offers to carry the Ring for Frodo for a bit, even though he knows Frodo will reject this offer.
Frodo tells Sam that he literally cannot give the Ring up at this point. He would go nuts if he tried.
Frodo and Sam decide to get rid of all of their orc gear. Let's face it: they don't need anything weighing them down at this point.
Frodo pushes on, seeming to have regained some strength.
But by the end of the day, he lies down and says only, "I'm thirsty, Sam" (6.3.35).
Sam resolves that he will get up that mountain with Frodo no matter what—even if he has to carry him.
They reach the base of Mount Doom, exhausted, cold, and in pain. So close.
Frodo falls to his hands and knees and starts crawling up the side of the mountain.
But Sam comes to the rescue and carries Frodo on his back towards the Cracks of Mount Doom.
Finally, when Sam can't continue anymore, he sets Frodo gently down. Frodo thanks him with a whisper.
Sam looks up and realizes that they are already more than halfway up from Gorgoroth Plain. Then he sees a path carved into the side of the mountain.
This is Sauron's Road from Barad-dûr to Sammath Naur, the Chambers of Fire, and it's always kept clear to give Sauron access to the Mountain's furnaces.
Too pooped to process this information, Sam lies down right on the spot.
But suddenly, Sam and Frodo both feel this odd sense of urgency, so they get to crawling again.
Frodo looks over to the topmost tower of Barad-dûr, and for one brief moment, he sees the Eye.
The Eye is (luckily) not looking at Sam and Frodo; it is staring at the Morannon where Aragorn's troops are massed.
But even that brief glimpse of the Eye destroys Frodo.
He whispers, "Help me, Sam! Help me, Sam! Hold my hand! I can't stop it" (6.3.64).
So the hero of the hour picks Frodo up on his back again and struggles further up.
Of course it can't be that easy. Sam feels a sudden weight, and he crashes to the ground.
It is Gollum, shrieking. Not good.
Gollum feels betrayed, now that he sees that Frodo wants to "hurt Preciouss" (6.3.67), so he demands the Ring, and attacks Frodo.
Furiously, Frodo fights back. He's unwilling to let Gollum take the Ring from him.
Sam tells Frodo to hurry on; he'll deal with Gollum.
Frodo agrees, and wishes Sam farewell.
Sam leaps at Gollum with his drawn sword.
Gollum falls flat on his face and whimpers.
Sam is so angry that he wants to kill Gollum, but there is still something inside him that stops him. Finally, he feels pity for Gollum, and decides to let him go.
He hurries up the path after Frodo, but when Sam reaches the Sammath Naur, it's so dark that he can't see, well, anything.
He pulls out the Phial of Galadriel, but it gives no light here.
Sam sees a deep fissure, which gives off the red glare of a volcano.
He sees Frodo standing at the edge of this fissure, and Frodo shouts, "I will not do this deed. The Ring is mine!" (6.3.89).
Frodo puts the Ring on his finger and disappears. This is a Serious Problem.
Something hits Sam in the back, and he is knocked out for a second.
Meanwhile, when Frodo puts on the Ring, Sauron realizes what he has overlooked.
He sees Frodo clearly for the first time, and he is furious and terrified at what might happen.
Our resident Big Bad sends the Nazgûl racing to the Cracks of Mount Doom, where Sam stands up to see Gollum struggling furiously with an invisible enemy.
Gollum bites, and Frodo cries out and reappears, clutching his hand.
Sneaky little Gollum dances at the edge of the crack, screaming, "Precious, precious, precious!" (6.3.93).
But he overbalances and falls into the fires of Mount Doom.
Suddenly, there's a big ol' roar and the mountain shakes.
Sam carries Frodo out the tunnel and has a vision of all of Mordor falling at once.
The Nazgûl disappear in the ruin of Mount Doom.
Frodo turns to Sam.
He looks like himself again, free of his burden.
Sam falls to his knees with relief at seeing Frodo sane once more.
But he notices that Frodo's hand has been maimed. It's missing the finger that carried the Ring.
Frodo tells Sam to forgive Gollum, because without him, Frodo could never have completed his quest. Go figure.
Now it is all over, and Frodo is glad Sam is with him.