1891. June Buckley arrives in Kansas City to claim the inheritance of a father she never knew - but she's not the only heir. Summoned alongside a volatile group of strangers, June is forced to travel by horseback to a remote ranch where the will is to be revealed. Under the watch of executor Temple Houston, they must follow the exact path her father once took into the frontier. But the journey turns deadly when June is assigned Hendido - a massive, violent horse feared by all. After a brutal outburst, the creature mysteriously bonds with her, marking June as something more than just another heir. As the group pushes deeper into the wilderness, paranoia grows, alliances fracture, and it becomes clear the journey is no formality - it's a test. And not all of them will survive it.