The Rifleman is the top-grossing film of all time at the Latvian box office and if you had to guess at the kind of film that would inspire such nationwide enthusiasm, you’d guess it was something like this: a lavishly mounted, lion-hearted first world war epic based on a book banned by the Soviets for 60 years.

Oto Brantevics stars as Arturs, a 16-year-old who signs up in 1915 to fight the Germans, alongside his brother Edgars (Raimonds Celms) and father Vanags (Martins Vilsons). Both Arturs and his dad are outside the required age range for the army, but rules are bent on account of the father’s exceptional marksmanship. Thus, three men of the same family set off to war, fighting sometimes for the Tsar, sometimes for the Red Army – but always, really, for each other.

Blizzard of Souls, the 1934 novel from which this is drawn, is based on author Aleksandrs Grīns’ own frontline experiences, and The Rifleman successfully captures the hazy, gauzy quality of memory. This works well in early scenes, when Arturs is frolicking on the family farmstead or skinny-dipping in the sea with the rest of his battalion. Less so in the battle sequences, where any sense of jeopardy is muffled by a thick layer of nostalgia and prettified by a dusting of sparkly snow.

While the fur hats are pure Doctor Zhivago, the emotions never feel quite so epic. This means that The Rifleman’s most intriguing presence – Greta Trusina as Arturs’ love interest Marta – is left with little to do. Brantevics convincingly portrays Arturs’ four-year transformation from a callow youth to a war-weary one, but as a national coming-of-age story, The Rifleman never quite outgrows its innocent, uncritical patriotism.

• The Rifleman is in cinemas from 26 July.