James Gray's painterly, meditative style goes down well with film festival enthusiasts. But it's an unusual approach for what half pretends to be a manly, action-adventure saga, the true story that inspired Arthur Conan Doyle's The Lost World. Based on a best-selling work of non-fiction by The New Yorker's David Grann, it chronicles the perilous, calamity-strewn Amazonian expeditions of British army officer Percy Fawcett.

Fawcett heads to the Amazon in 1906 at the behest of the Royal Geographical Society to map the uncharted river boundary between Bolivia and Brazil. Much hacking through the jungle with machetes ensues, along with scary critters, blood poisonings, feverish interludes of river rafting, starvation and ambushes by cannibals.

When this enthusiastic explorer uncovers remnants of ancient pottery and carved faces deep in the jungle he becomes obsessed with finding proof of an ancient, sophisticated civilisation, a lost city he called 'Z'; a theory disputed (at least in this version of events, groping for some political tension) by imperialists who view Amazonian tribal peoples as primitive savages to be exploited. Fawcett would return to the area on lengthy, arduous journeys over 20 years – interrupted by WWI and heroics at the Somme – accompanied by two faithful companions, the odd cowardly saboteur, and finally his eldest son Jack (played by new Spider-Man Tom Holland), until his disappearance in 1925 became a tantalising mystery, the stuff of legend.

As Fawcett, Charlie Hunnam is an attractive model of level-headed, courteous, stiff-upper-lipped Britishness. He is driven, it is suggested, to restore his family name and status with exceptional deeds (after the caddish behaviour of his father), and gradually gripped by a philosophical yearning to lose himself in some intangible cosmic destiny. As his sidelined wife Nina, left for years at a time to raise their children, Sienna Miller pluckily makes what she can of an improbably forward-thinking proto-feminist but is largely off camera between brief reunions. An almost unrecognisable bearded and bespectacled Robert Pattinson hones his character actor credentials nicely enough as Henry Costin, the loyal, taciturn sidekick who has Percy's back from jungle to battlefield and back again.

The cast cannot, however, overcome a languorous and sometimes confusing narrative, too many sketchy characterisations and an exquisitely staged but bafflingly transcendental ending. Gray can't escape the long shadows of Werner Herzog's Aguirre, the Wrath of God and Fitzcarraldo – there is even a surreal scene in which our intrepid Brits come upon an opera company in the middle of nowhere – and the real star of the show is Darius Khondji's superb cinematography. Those venturing in anticipating Indiana Jones-style thrills are in danger of finding The Lost City of Zzzzs.

General release from Fri 24 Mar.