The final four chefs are headed to Tucson. For their last Quickfire Challenge, they'll make the trip to El Charro, the oldest family-run Mexican restaurant in the country, where legendary chef Carlotta Flores challenges them to create a dish featuring her Carne Seca. In the final Elimination Challenge, alum and Tucson local Maria Mazon wants the chefs to embrace the desert lifestyle and create two dishes--one sweet and one savory--using the classic Sonoran ingredients: cactus and chiltepin. With an impressive assortment of locals and "Top Chef Seattle" winner Kristen Kish joining the judges table, the heat is on.