In the 18th century, artist Langdon Towne and his friend Hunk Marriner get into trouble in their hometown of Portsmouth, New Hampshire. After a drunken altercation, the pair flee toward a distant military fort. There, they encounter Major Robert Rogers, the leader of Rogers' Rangers, a special elite military group. Rogers enlists them for an arduous expedition through uncharted wilderness with the goal of punishing the Abenaki tribe responsible for attacks on British settlers. Langdon joins, partly out of necessity and partly driven by the allure of adventure and the opportunity to document the journey through his art.

The trek is grueling and fraught with peril, testing the limits of both the group's endurance and camaraderie. Along the way, they face challenging terrain, scarce supplies, and the constant threat of enemy forces. However, under Rogers' determined leadership, they push forward, driven by the mission's importance and their loyalty to each other. The expedition's success not only holds strategic significance for the British forces but also represents a personal journey for Langdon and Hunk as they confront and overcome their own limits.