Mandela: Long Walk to Freedom is adapted from the late great man’s autobiography about his “lonely road . . . not over yet.” Not so effective as the superior Jo Menell-Angus Gibson documentary treatment or TV movies with Danny Glover and Sidney Poitier or Clint Eastwood’s more recent Invictus, which benefits from Morgan Freeman and a reduced-issue scope, this Justin Chadwick biopic offers no surprises in technique or script (by William Nicholson) but is nevertheless a notch above average. It would have been a benefit, however, if African rhythms had been used in place of the audience-aimed U2.

Attending the London première just last Christmas, Zindzi and Zenani received word of their father’s death but requested that the film be screened with no announcement until after the closing credits. Over two-and-a-third hours long, it does a credible job of cramming in a lot, both personal and national. Opening like autobiography in a brief present in which Mandela (Idris Elba) gives voice to recurrent dreams of rural Orlando boyhood, it hints at nostalgia for Xhosa-speaking simplicity and desire for parental approval, willingly sacrificed to external circumstances and freedom for the nation’s blacks and whites alike.

Impeccably three-piece suited, the young lawyer he became in partnership with Oliver Tambo (Tshallo Sputla Chokwe) is at first unimpressed with the activist agitation of the new African National Congress. Pretoria’s 1948 Apartheid grows ever more brutal and repressive, reaching a flash point in the 1960 Sharpeville Massacre of sixty-nine unarmed black demonstrators, steering the natty lawyer and amateur boxer towards armed resistance and sabotage as commander of ANC-related Spear of the Nation.

Worry about the children and anger at his neglect and a sexual liaison drive first wife Evelyn (Terry Pheto) to divorce him, but he is shortly involved with, then married to, the revolutionary Winnie (Naomie Harris). His safe house on a farm no longer safe, he is being escorted to another but is intercepted by police, to be put on show trial with fellow “guerrilla warfare terrorists.” So as not to martyr them by execution, the judge sentences the group to life imprisonment at rock-breaking labor.

Through snips of archival footage but mainly well-done recreations, the film summarizes violent polarizing events within the country, as well as internal and international reaction to them, during the prisoner’s eighteen years on Robben Island and nine more in somewhat less harsh Pollsnoor Prison. While he rather than the others becomes the recognizable face of cause célèbre, it is made clearer why and how Winnie becomes more adamantly militant in her hatred of whites, but there is no probing the depths of Nelson’s essential shift towards forgiveness, reconciliation and coexistence as the sole hope for the crying beloved country.

Perhaps genius is in the end inexplicable.

His supporting film characters are given short shrift, and drama is filled in with bits such as his winning them the issuance of long trousers instead of boys’ short pants or outfacing newer young prisoners who find veteran ANC founders old-fashioned namby-pambies. It is not shown and must be taken on faith that his legal background and inborn character combine to equip him to deal with, and convince, beleaguered minister Kobie Coetzee (Deon Lotz), President Frederik Willem de Klerk (Gys de Villiers) -- with whom he would later share the Nobel Peace Prize -- and more reasonable or malleable ANC partisans.

Winnie proves a harder nut. Though the film says that he loves her, personal and familial priorities must be weighed against the needs of the nation and the good of the many. Leadership comes often at a steep price.

(Released by the Weinstein Company and rated “PG-13”for some intense sequences of violence and disturbing images, sexual content and brief strong language.)