Principal photography is under way on acclaimed South African helmer Khalo Matabane’s gritty new prison drama “28.”

Based on the award-winning book “The Number” by Jonny Steinberg, the film is a hard-hitting exposé of the origins of the vicious gangs operating in the South African prison system.

Pic stars Mothusi Magano (“Tsotsi,” “Hotel Rwanda”) as Magadien, a hardened career criminal who swears a blood oath to members of the 28s gang. Faced with a sudden change of heart, he decides to risk his life and break his bond to the brotherhood, whatever the consequences.

While researching the film, Matabane (“State of Violence,” “Conversations on a Sunday Afternoon,” “Nelson Mandela: The Myth and Me”) spent years with the real-life Magadien Wentzel in Cape Town, and also immersed himself in the lives of ex-prisoners to better understand gang language and culture.

“It is a story of a man struggling with himself, in turmoil,” says Matabane. “He has done terrible things in his life and is searching for forgiveness from his family.”

Along with Magano in the lead role, Matabane and casting director Moonyeenn Lee assembled a cast of top local talent including Warren Masemola, Sibusiso Msimang, Presley Chwenegyagae, Lemogang Tsipa, Kevin Smith, and Deon Lotz. Acclaimed activist, storyteller, poet and playwright Gcina Mhlophe plays Magadien’s mother.

The production team is headed by producers Carolyn Carew and Tsholo Mashile. Anant Singh’s Videovision Entertainment are co-producers, and will also distribute the film.

Pic marks the first co-production between South Africa and Reunion Island’s Tiktak Prods. The film received funding support from the KZN Film Commission, the National Film & Video Foundation, and the Dept. of Trade and Industry.