With films like The Immigrant and Two Lovers, James Gray has built a career exploring the most intimate of machinations in personalities and relationships, building a leaning yet prestigious oeuvre of work despite box office numbers. With his newest film, Gray tackles the David’s Grann’s 2009 non-fiction work The Lost City of Z, chronicling the British explorer Percy Fawcett’s harrowing exploration of South America and his quest for a mythic city reputedly offering proof of technological advancement in a non-literate culture. Despite the evocative Indiana Jones-esque title, Gray sidesteps swashbuckling, instead opting for a tale that probes the subconscious and unthinkable sacrifices in the name of exploration.

Charlie Hunnam stands in for the renowned cartographer, reluctantly agreeing to leave his stunning wife, played by Sienna Miller, and his children to spend two years mapping the uncharted the Amazon in order to advance his military career. But, while trudging through the jungle, a fever takes Fawcett. Not the kind brought on by malaria. He becomes enraptured by the story of an advanced civilization that improbably once thrived deep in the wild.

Propelled by the discovery of pottery and tools, Fawcett mounts another expedition to find the lost city. The film takes pains to convey just how dangerous these types of journeys were early in the 20th century. Fawcett’s excursions were plagued with sickness and attacks from native tribes; both claimed lives. Still he persisted to find proof that Z existed. Hunnam, best known for his more conventional roles, admirably finds his footing as a leader of men in the wilderness spurred on by a deep-seated longing. The impressive supporting cast, including Miller, Robert Pattinson and Tom Holland, each make their mark to this careful study of a once-ridiculed explorer.

If some viewers find Gray’s film dissatisfying, it won’t come as a surprise. Like spending billions to collect Martian rocks, the very edge of great exploration is usually not like Geraldo Rivera opening Al Capone’s secret vault on live television. More often, it’s meticulous, uncelebrated work. However, with mesmerizing, dreamlike imagery and lean, stalwart performances, Gray pays homage to Fawcett’s story and why chasing the unknown will forever be a tenet of man’s path forward.