He made a notable splash on the international festival circuit in 1974 with The Earth Is A Sinful Song (1973), his debut feature, an earthy, erotically-charged, blood-soaked tale of a young village girl's ill-fated affair with a Lapp reindeer herdsman.

Based on a novel by the late Timo K. Mukka, one of Finland's most controversial young writers, the film "stunned Scandinavian critics and audiences alike with its simple, terrible power and its authentic sensuality" (Peter Cowie), and went on to become one of the biggest box-office successes in the Finnish cinema's history.

It also introduced Mollberg's trademark style: "a realistic naturalism full of expressive force with which he merges the people with the scenery, stripping them bare of life's illusions and the polished veneer of culture" (Sakari Toiviainen).

Despite Peter Cowie's efforts, and the acclaim of many other critics and "independent" festivals, The Finnish National Film board has stubbornly sequestered this masterpiece, only releasing it in a DVD format incompatible with international viewing, and lacking English subtitles.

[3] 590,271 tickets were sold for the screenings of The Unknown Soldier (1985) making it the 17th highest-grossing movie in the history of Finland.