The camp is attacked by a band of orcs and Boromir is killed. Before he breathes his last breath, Boromir tells Aragorn that the orcs have carried off the other hobbits. The remaining members of the party search through the bodies of dead orcs and find many weapons. They put Boromir's body on a raft and set it out to sail, having no time for any other kind of funeral.
Aragorn tells Gimli and Legolas that he thinks Frodo and Sam have gone alone to Mordor and that they themselves should follow the orcs and not Frodo. So saying, these adventurers continues on their journey, travelling in search of their missing companions.
Boromir's death redeems his last act, because he dies a hero. Aragorn is careful to give him a hero's funeral, as much as possible. After that, the men must resume the business at hand of finding their lost companions Merry and Pippin.
On their journey, Aragorn, Legolas, and Gimli come across a pile of slain orcs and come to the conclusion that the orcs have quarreled among themselves. Still there is no sign of Merry and Pippin. Later, they find hobbit footprints and a broach--clues that their captured friends have passed this way.
After many days of pursuit without sign of trail or hope, Aragorn sees riders coming their way. The riders are men of Rohan and their leader is Eomer. Eomer and his riders tell the men that they have already slain the orcs but that there were no hobbits with them. When Aragorn tells Eomer that both Gandalf and Boromir are dead, Eomer is sorry. He tells the hunters that the men of Rohan are no friends of either Sauron or Saruman, the wizard who was aiding in the attack on Boromir's people. He offers the hunters horses, asking only that once their deed is accomplished, they return. It seems Eomer's king, King Theoden, did not want him to aid the travelers.
After bidding farewell to the men of Rohan the three hunters again pursue their hobbit friends. At night they rest under some trees in the forest of Fangorn. Gimli, who is on guard, sees an old man but before they can discover who he is, he disappears. The horses are gone as well. Gimli tells the others that he thinks the old man was Saruman, who has taken or scared away their horses. Their dim hope of catching their friends grows even fainter.
The narrative remains with Aragorn, rather than Frodo. For the time being, he and his companions are focused on finding Merry and Pippin. The search, like much of the plot, proves more difficult than it had seemed.
Pippin and Merry, in the custody of the orcs, lie captive awaiting their fates. By listening to the conversation, Pippin learns that there are two groups of orcs. In the course of taking the captives, the two groups have fought one another. Pippin gets hold of a knife and cuts his bonds, tying a loose knot around his wrists.
The prisoners are picked up and after another short journey, the orc's messenger tells them that a single horseman was seen nearby. This time Merry and Pippin are made to walk instead of being carried. Pippin manages to break free, but is caught. Fortunately before he is caught, he manages to lose his cloak pin, a broach. He loses consciousness and only regains it when the orcs stop.
Eomer and his men attack the orcs and Merry and Pippin manage to escape into Fangorn.
This chapter is a sort of narrative flashback, explaining the pin that the other men found in their search. This narrative layering reveals a thoroughness on the part of Tolkien, who wants to explain all the loose ends he includes.