Fast-paced adventure meets art history in the fourth book of this thrilling series! Georgia O'Keeffe's Red Clouds with the Pedernal serves as the backdrop for Tiger and Luna's ongoing mission that allows them to enter the worlds of famous paintings. As they search for David, the boy who's been missing inside the frame for fifty years, they must traverse the desert and climb the mountain in New Mexico sacred to Native American tribes. But could the stories about spirits on the Pedernal be true? It's just one more detail for Tiger and Luna to keep in mind. But they must also remember the most important thing of get back to the real world before the end of the hour, or remain stuck in the painting forever!