AS THE lights in the cinema go down and the patrons take their seats, the familiar Warner Brothers logo lights up the room and the soundtrack starts. This, however, is no ordinary cinema. The roof is of corrugated tin; the seats are tree trunks. The viewers watch a flat-screen television. As the movie, “Deep Blue Sea 2”, begins, Fred Ndichu, the DJ, starts his work. In a booth with an ancient computer, a wad of qat (a mild amphetamine) sticking out of his rapidly moving mouth, he begins to narrate. “Beautiful”, he shouts in Swahili, as a great white shark tears apart a flailing fisherman on-screen.

Mr Ndichu’s cinema, named the innocuous “Heshima Youth Group” to deter bribe-demanding cops, is in Mathare, a rough neighbourhood of tin shacks in eastern Nairobi. Similar establishments exist across the city, and in some other African countries. At the weekend the shack fills up with men watching English Premier League football. On weekdays it is given over to cinema. But whatever the film, it must have a DJ. The DJ’s job is not just to translate English into Swahili. It is to translate—indeed explain—the entire movie.

  • Trade talks expose a chasm between China and America

  • A huge interest rate hike has arrested a run on the Argentine peso

  • America’s Treasury ramps up borrowing to finance the Republican tax cuts

  • A healthy re-examination of free trade’s benefits and shocks

  • Iowa passes one of the harshest abortion bills in America

  • Council elections in England reveal political stasis

Mr Ndichu, adds commentary and explains cultural differences. “Only if you have a DJ who knows what he is doing, can you fully understand a movie,” he insists. The most popular films are typically bloody action movies. These are easy to explain. A tougher challenge, but worth it, was a film about Edward Snowden. “When I explained to the customers what it meant, they loved the movie, but they hated the CIA,” he says.

The business is not lucrative. A viewer typically pays 10 Kenyan shillings ($0.10); at most, the shack can cater for 30. Out of that must come rent plus the cost of DVDs and occasional bribes. Mr Ndichu hopes to make more money by recording his performances and selling them to other budding cinema owners. With ancient video-editing software, he puts together a package and burns it to DVD. The trouble is that pirates quickly copy his work, so he cannot charge much.

In Nigeria, slum cinemas have spawned a film industry. In Kenya, filmmakers are scarce. But that may be changing. In February “Supa Modo”, a touching Kenyan film about a terminally ill child’s wish to be a superhero, was played at the Berlin film festival. True to Kenyan form, one of its characters was a movie DJ called Magic Mike.