Heart of a Lion follows cougar biologist Mark Elbroch into the parallel worlds of two mountain lion mothers: F61, who revealed their hidden social lives, and Yoko, struggling to raise her young on the edge of human encroachment. From the rugged wilderness of Wyoming’s Tetons to the misty forests of Washington’s Olympic Peninsula, this intimate and immersive journey reveals one of North America’s most misunderstood predators—asking us to see them with admiration instead of fear.