In an effort to discover more about the desert tortoise, host David Yetman treks from the dry deserts of Utah to the tropics of Northwestern Mexico in search of these special animals. The trail begins outside of St. George Utah, which has more tortoises there per square kilometer than anywhere else in the United States. In the Mojave Desert, Yetman observes how tortoises are marked and then tracked using telemetry. The goal of this study is not only to monitor the desert tortoises' path, but also to study their behaviors and the effects of changing land use. The task is not as easy as it may sound, because these creatures are actually capable of moving 25 miles in one season. The Desert Speaks also visits some of the happy homes in the Sonoran Desert that have benefited from the Arizona-Sonora Desert Museum's Desert Tortoise adoption program. Finally Yetman tracks down some fellow-trackers in search of the southernmost tortoises, near Alamos, Sonora.