This musical about the extraordinary life of the South African freedom-fighter turned statesman promises so much. Backed by members of his family, it is led by Broadway talent including Michael Luwoye in the lead role and director Schele Williams. And it begins powerfully, with the Sharpeville massacre of 1960 when peaceful protest was brutally ended by machine gunfire and dozens of deaths. But for a two-and-a-half-hour production it is astonishing how little we learn about the main players, from Madiba to the African National Congress colleagues who surrounded him, as well as Winnie Mandela and their children. Instead it offers a vague and sentimental sweep of his life, focusing on his prison years on Robben Island. There is a minimal book by Laiona Michelle that speaks in slogans and brings little dramatic tension, with cursory or shallow exchanges between characters. Some of the music by South African songwriters Greg Dean Borowksy and Shaun Borowsky is rousing, especially when accompanied by the dancing ensemble who bring some energy. But more often the songs are syrupy, ponderous and inert. We find out nothing about Mandela’s background – meeting Winnie, training in law, his path into ANC activism or his Marxist brand of socialism. Mandela speaks of fighting fire with fire but there is little insight or detail beyond these banner words and phrases, which come to sound like fridge magnet philosophy. “No talking politics,” barks the guard at Robben Island when Winnie visits Mandela, and this seems like a policy for the musical too. We get brief glimpses into the life of Winnie (Danielle Fiamanya) but the controversies around her leadership – alleged violence and corruption – are broached in one song and swiftly put away. As a family story, there is a moving scene when Mandela is prevented from going to the funeral of his son who has been killed in a car crash, but more often scenes with his children are filled with sugar and schmaltz, Mandela’s daughters dreaming of their tall, dark, handsome daddy, his sons joshing or sparring with him. The central performances are as strong as they can be given the material, and both Fiamanya and Luwoye’s voices brim with power, as do those of the chorus. But that is simply not enough and this feels like a thoroughly missed opportunity. At the Young Vic, London, until 4 February