Quietly, patiently, trees endure. They are the oldest living beings we come to know during our time on earth. They provide our shelter, our fuel, our companions, and—in some cases—our divinity. They are living bridges into our planet’s enormous past, their obscure stories written into their rings over centuries and even millennia. Treeline takes us to the enshrined cypress groves of Japan, the towering redcedars of British Columbia, and the ancient bristlecones of Nevada, following a handful of skiers, snowboarders, scientists, and healers as they move through these giants and explore a connection older than humanity.