In the meantime, Gandalf rides to Isengard to seek the counsel of Saruman.
Saruman knows many things about the Dark Lord, like that he is preparing an army large enough to soon war against the free people again and conquer all of Middle-earth.
How does he know this? He has a Palantír (that seeing orb thing that was the Middle-earth equivalent of Facetime and Google) that allows him to communicate with and—oops—be corrupted by Sauron.
He tells Gandalf they have run out of time and their only choice is to join forces with Sauron, who is sure to be victorious once he possesses the ring.