"The Dark Divide" is based on the true story of renowned butterfly expert Dr. Robert Pyle's (David Cross) perilous 1995 journey across one of America's largest undeveloped wildlands. At the urging of his dying wife Thea (Debra Messing), the shy author finds himself in over his head on an epic, life-changing expedition through Washington's Gifford Pinchot National Forest in search of new species of butterflies. Over the course of his six-week adventure Pyle battles self-doubt, the grueling trail, and the people and creatures who call this forest home. And, somewhere deep in the heart of The Dark Divide, he makes a discovery that challenges everything he knows about the natural world.