Roots, BBC Four

Those of us who saw the first, 1977 TV adaptation of Alex Haley's Roots in our teens still remember the shock and horror at its handling of a subject about which we knew little, American slavery. We know a lot more now, but the visceral reaction to inhumanity and injustice is no less strong.

That's thanks to the high production values of the latest version, its gift for finding the right actors, and the often giddying cinematography of an honourable mainstream parallel to a towering masterpiece among movies, 12 Years a Slave.

Roots, originally commissioned by the History Channel, may be more predictable, staying to an extent within the parameters of a TV miniseries, but it also has a more epic scope as an ambitious tetralogy of two-hour dramas, each different in mood, skipping time and crossing generations as we get to know Kunta Kinte, the enslaved Mandingo warrior from Juffure sold into slavery on a Virginia plantation, and his offspring. By episode three, the branches are struggling towards the sun, The general drama of pain isn’t, by now, devoid of occasional episodes of happiness, and hope springs eternal with each new family member.

The casting is superb, instilling confidence in every major character and complicity in their hope. The first two episodes are Kunta Kinte’s story, starting with his adolescent training in the Gambia – the locations, well handled, are South African – and his betrayal by a local tribe (the original series had the toubabs – “whiteys” – as the impressers). It’s not hard to believe in Kunta’s indomitable pride given the magnificent performance of former EastEnders and Doctor Who actor Malachi Kirby.

Sympathy soon extends to the old slave musician on the plantation, played by the infallible Forest Whittaker, and – jump forward 10 years in episode two – to Belle (a luminous Emyatzy Corinealdi, pictured above with Kirby). She's the wise woman who nurses “Toby”  – the slave name Kunta refuses to accept – back to life and hope after his cruellest punishment.

I challenge you not to wince and groan aloud at the tribulations of the family, the sunderings and cruelties which would seem the stuff of fiction did we not know how often they happened. Their stylised depiction – scenes of extreme violence often shown with sound levels reduced and careful camera angles – only heightens the strangeness. After the rape and birth-giving of Kunta and Belle’s daughter Kizzy (equally well played by the young Emyri Crutchfield and the older actor Anika Noni Rose), the action can afford to relax a little.

Episode three focuses on Kizzy’s son Chicken George (Regé-Jean Page, pictured right, as winning in his way as Kirby), the boy who has a way with birds and grows up in the hope of buying his freedom. The new location also gives us the first toubab owner who isn’t a cardboard cut-out (and one of the few, in the shape of Jonathan Rhys Meyers’ Tom Lea, who can sustain an accent). Family wrenches here come in the ambivalence of the triangle between father, mother and son, the way we actually hope, as George does, for Lea’s survival in a duel, and the ultimate betrayal (Irish blood can turn a man to drinking and gambling in these cinematic sagas).

This first Chicken George instalment starts out as Roots’ equivalent of the third opera in Wagner’s Ring, the tale of the brave young Siegfried who looks as if he might redeem the world (don’t laugh: the epic resonances are not so impertinent). In the wake of Nat Turner’s slave rebellion, though, it all turns darker and the episode ends on another cliffhanger. Through Haley’s telling of his ancestors’ stories, we know it must all turn out well in the end. But what colossal suffering and injustice along the way. For the viewers, and how much more so for the actors involved, the knowledge of that past only heightens the involvement in this nuanced and poetic telling of America’s (and Britain's) most shameful history.

• Read more TV reviews on theartsdesk