Doc is getting the heck out of Lost Forest, and Mark is (finally) away and (mostly) on his own…
According to Wikipedia: The Sonoran Desert (Spanish: Desierto de Sonora) is a North American desert which covers large parts of the Southwestern United States in Arizona and California and of Northwestern Mexico in Sonora, Baja California, and Baja California Sur. It is the hottest desert in Mexico. It has an area of 260,000 square kilometers (100,000 sq mi). The western portion of the United States–Mexico border passes through the Sonoran Desert.
Let’s see what kind of trouble they can find!!
The Daily Trail 
Sonoran Desert caves are prime habitat for the endangered light-emitting moss cartoonis fictivis, though Mark will not write a story about it.
A favorite location for cross-border cartel transportation and also for illegal entries by desperate people. Let’s add them to the list of possible problems Mark and Doc may run into.