The image of Gollum guiding Frodo and Sam through a barren landscape on their way to fulfill their mission echoes similar images from the ancient Greek and Roman epics. Tolkien, who was well studied in the classics, was very familiar with epic tales like the Odyssey and the Aeneid, in which the protagonists must suffer through a distressing journey to the underworld, often guided by somewhat shady or unsavory characters. On these ancient journeys, the heroes often must confront the dead, along with the possibility that they themselves may die as well. In The Two Towers, Gollum leads the hobbits through the Dead Marshes, a realm of the dead, with waters that contain ghostly images of the faces of slain warriors. Much like the realms of the dead in the classical epics, the landscape of the Dead Marshes is deeply unpleasant, devoid of life and growth. Yet passage through this barren landscape is a necessary step for the ultimate completion of the quest. As Gollum emphatically points out, there is simply no other way to reach Mordor, just as in the classical epics there was no way for the heroes to complete their quests without a sojourn in the underworld.
Mordor continues to become an ever stronger and darker reality in the novel. As the hobbits approach the dark land, it becomes a clearly felt presence. The landscape bordering Mordor is noticeably nasty, full of poison pits and barren stone outcrops, with an overwhelming stench saturating the air. The frightening Nazgûl flying overhead are a constant reminder of the proximity and threat of Sauron. Even the normally solid Gollum is deeply spooked when the Nazgûl flies overhead for the third time, taking it as a very bad omen. This growing atmosphere of evil, along with the uncertainty surrounding Gollum’s trustworthiness, increases yet further the suspense that propels Book IV forward.