Victory is sweet. Théoden goes to greet Gandalf, along with Aragorn and Legolas. They also reunite with Gimli, Éomer, and Gamling, who all survived the battle. Aw, the gang's all together again.
Éomer asks how Gandalf managed to bring all these trees here, but Gandalf swears he had nothing to do with it. It's just a stroke of awesome luck.
But on to business: Gandalf wants to go at once to Isengard.
Théoden is against this. They do not have an abundance of troops to attack Isengard.
But Gandalf has his mind made up. He's going, no matter what.
Théoden decides that he will trust Gandalf: "I will come with you, if that is your counsel" (3.8.20).
They decide to rest for the day and set off in the evening. Legolas, Gimli, and Aragorn agree to tag along, of course.
As they ride off, all the men, women, and children who had been sheltering in the caverns of Helm's Deep come pouring out singing songs of victory.
They ride through the new (and rather forbidding) forest that has collected around Helm's Deep.
Legolas seems quite taken with the forest. He senses that the trees come "from the deep dales of Fangorn" (3.8.46). Seriously, what is with this dude and trees?
For his part, Gimli is in love with the caves of Helm's Deep (which are called the Glittering Caves of Anglarond). Well, we all knew that Gimli loved rocks, so we guess that's no surprise.
Legolas and Gimli make a promise that, if they both survive the war, Legolas will go with Gimli to Helm's Deep and Gimli will go with Legolas to Fangorn.
At last, they emerge from this strange forest.
As they leave the cover of the trees, Legolas freaks: he sees eyes among the trees.
Suddenly, three great shapes, like trolls but not, you know, horrible, emerge from the trees.
Gandalf tells everyone not to panic: it's fine; they are just herdsmen. Whatmen?
Théoden asks the question everyone must be thinking: but what are they herding?
Gandalf patiently explains what we already know: these are Ents.
He reminds Théoden that the people of Rohan call Fangorn Entwood.
At last, they arrive at the River Isen, which seems almost drained of water entirely.
Beyond the river, there is a mound piled with rocks and covered with a bunch of spears. This turns out to be a grave for the Riders of Rohan who fell in battle with the forces of Isengard before the Battle of Helm's Deep.
Gandalf was one of the people who helped build it, but he wasn't the only one.
Still, he will not say more about who his helpers are.
When they reach the foot of the Misty Mountains and the vale of Nan Curuní, they see billows of smoke rising from the Wizard's Vale.
Late in the night, the watchmen see darkness spreading towards them going north.
Gandalf tells them not to worry, and to draw no weapons.
They hear "whisperings and groanings and an endless rustling sigh" (3.8.97). There is no one and the darkness passes eventually.
Back in Helm's Deep, the same thing happens through the night.
The next morning, the people emerge to see that the orc carcasses are all gone from the battlefield—and so are the trees.
The hill where the trees had stood has always been bare since then, and it is called the Death Down.
Meanwhile the River Isen suddenly begins bubbling as usual.
Orthanc has been a strong place, without a trace of green, but it is also just a pale imitation of Barad-dûr, that "furnace of great power" (3.8.107) in Mordor.
When Théoden and the rest arrive at the once-strong Orthanc, they find that the gates have been pulled down and there is water lapping right at the walls of the tower. Looks like Isengard isn't so powerful anymore.
But the strangest thing of all is that they see two small figures sitting on a rock among the rubble. One is asleep, and the other seems to be smoking.
Théoden and Éomer stare in amazement.
The figure who had been smoking leaps up and says, "Welcome, my lords, to Isengard! [...] We are the doorwardens, Meriadoc, son of Saradoc is my name; and my companion, who, alas! is overcome with weariness [...] is Peregrin, son of Paladin, of the house of Took" (3.8.118).
Merry tells the crew that Saruman is inside with Wormtongue.
Gandalf laughs and asks who commanded them to watch the doors.
It was Treebeard who is now in charge of Isengard.
Gimli asks why they have no words for their old friends, Legolas and Gimli?
Gimli could not be more surprised to see these two "woolly-footed and wool-pated truants" (3.8.118). We're betting he's more than just surprised, though. He's probably downright ecstatic.
Théoden realizes that these two must be the lost members of their Company.
He asks if they are Halflings, or what the people of Rohan call "Holbytlan" (3.8.122).
Pippin offers: "Hobbits, if you please, lord" (3.8.123).
Merry starts giving a history of hobbit pipe-smoking, to which no one pays much attention.
Gandalf warns Théoden that hobbits can talk about Shire affairs no matter where they are—even on the edge of a ruin.
Anyway, the hobbits aren't the only guards. There are also Ents surrounding the tower.
Merry has a message: if Gandalf and Théoden ride to the north wall, they will find Treebeard waiting for them.
Pippin mutters to Merry as they go: "So that is the King of Rohan! [...] A fine old fellow. Very polite" (3.8.139).