Pode ser O Wayfinder de Darcy Pattison. Descrição da Goodreads:
Young Winchal Eldras is a Wayfinder, one of the gifted few of G'il Rim who have the ability to locate anything: a lost ring, the way home, a blue dress in the marketplace, a lost child. "Finding" is a valuable talent in this city that sits dangerously close to the Rift, a mysterious, unexplored chasm. When the Rift claims his little sister in a bizarre accident, though, Win is reduced to a Wayfinder who's lost his way. But suddenly there's no time for grief--the plague has come to the Heartland. And only healing water from the Well of Life, on the other side of the Rift, can stop it. A prophecy commands that Win must make the terrible journey to seek the Well. But no one has ever braved the dangers of the Rift and returned to tell about it! To make matters worse, Win suddenly has a traveling companion in Lady Kala, a prized-and royally stubborn--Tazi hound with a few gifts of her own. A Wayfinder with no direction can't possibly manage this imperious creature from the King's kennels, much less save a civilization on the edge of destruction.
Winchal Eldras is an apprentice Wayfinder, a member of an elite group of people who can locate anything or anyone. When Win’s little sister slips out of the house one foggy night, he tracks her to the edge of the Great Rift, where his fear of heights causes him to freeze, and she falls to her death. Bereft, Win retreats into himself. Then a prince of the Heartland arrives with news of a rapidly spreading plague and taps Win to journey through the Rift to find the Well of Life, whose waters are the only cure. With resignation, Win begins the arduous trek, joined by Lady Kala, a royal gazehound with her own special powers. The pair winds its way past a giant eagle, a deadly crocodile, a venomous tatzelwurm, and other dangers.