"The Border Trilogy" is a series of three novels by author Cormac McCarthy, consisting of "All the Pretty Horses," "The Crossing," and "Cities of the Plain." Set in the American Southwest and Mexico, the trilogy explores themes of love, loss, and the search for identity against the backdrop of changing landscapes and cultures. The story follows the journeys of two young cowboys, John Grady Cole and Billy Parham, as they navigate the challenges of life on the border. Each novel delves into their experiences with family, friendship, and the harsh realities of the world, ultimately reflecting on the complexities of human existence.