We’ve seen Aragorn look into the palantír, a direct challenge to Sauron’s might and authority. We’ve seen the Witch-king leaving Mordor with his armies. Sauron is desperate to crush any resistance to his rule of Middle-Earth, and whatever long game he was playing is officially over.
As Pippen chats up Beregond at the outer wall of Minas Tirith, five Nazgûl swoop over a group of men on horseback; Faramir has returned, and the Enemy is in hot pursuit.
Thrown from their beyond-frightened horses, the men make a run for the gate on foot. One Nazgûl gets Faramir in his sights, but Gandalf, riding Shadowfax, raises his hand and blasts a brilliant beam of white light into the Ringwraith. It shrieks and flees, the others retreating in kind.
Faramir is escorted to his father Denethor. When he sees Pippin, he tells of Frodo and Sam heading to Mordor via Cirith Ungol. Gandalf, to put it mildly, is not pleased. But Faramir notes that this was two days ago, so they could not have reached Mordor yet. This assault on Minas Tirith was not a result of their actions. Gandalf comes to the conclusion this must be a response to something Aragorn has done (which we know to be the case), but he has no way to confirm that until the Riders of Rohan arrive.
Denethor berates his son for cowardice, and says that Boromir would have brought him a “mighty gift” (i.e., the Ring). But Gandalf remarks that Boromir would have kept it for himself, and argument ensues. Denethor disapproves of the plan to send the Ring to Sauron in the hands of Hobbits. When they part, Pippin asks Gandalf of Gollum, who in turn notes some good may yet come of it.
Faramir is sent the following morning to the outlying ruins of Osgiliath as a first wave to protect against the forces of Mordor. The assignment is likely suicidal, but Faramir accepts. News arrives the following morning of a battle for the Pelennor Fields, nearby Osgiliath.
The Lord of the Nazgûl, aka the Witch-king, aka the Black Captain, leads the armies of Mordor, and Gandalf rides to Osgiliath to aid the fight against the Enemy. Another day passes, and Gandalf returns with the wounded. Faramir has stayed to fight, attempting a safe retreat. The armies of Mordor arrive in short order, Men and Orcs in black appear as far as the eye can see. Before them is a small band of, the last of Gondor’s rearguard retreating in panic. Denethor sends a small army of cavalry to protect the retreating men, and Gandalf rides with them, using his white light to hold back the Enemy. The men reach safety, but Faramir is injured when a Nazgul’s poison arrow finds its mark.
The city is besieged. Catapults rain fiery projectiles into and over the wall. Those trying to put out the fires come to the horrific realization that these are the burning heads of those forces Gondor lost at Osgiliath. Overcome with despair and grief, Denethor locks himself in the tower with Faramir, who is succumbing to his wound. Denethor curses Gandalf, weeping for his son and bemoaning the end of his lineage.
Gandalf takes command over the city’s defense, fending off the attacks to the outer walls. Meanwhile, Denethor orders arriving messengers that everyone in the city should give up and burn in the fires. He has Faramir carried to the Hall of Kings, the traditional tomb for the rulers and stewards. Pippin realizes the steward has gone mad when Faramir is laid on a marble table, and Denethor calls for dry wood and a torch. The Hobbit tries to get the servants to disregard the order, and released from duty, he leaves his post. He sends Beregond to intervene, then goes off in search of Gandalf.
The gates of Minas Tirith are hit with a battering ram; on the third strike, the doors shatter. The Black Captain enters the city, all fleeing before him. Pippin arrives to see Gandalf standing alone against the foe. The wizard orders the Nazgûl to return to Mordor, and the response is laughter and a drawn sword that bursts into flame. He readies himself to strike, but…
A cock crows. Horns sound from the north. The Riders of Rohan have arrived!