The London film festival has presented me with an exciting discovery this year: the South African film-maker Jahmil XT Qubeka, who brings some scalding steam-heat with a sensational noir thriller in black and white called Of Good Report. (It is actually his third feature, following two previous films, uMalusi and A Small Town Called Descent, which have yet to show up on IMDb.) Watching this brazenly shocking and gripping film, I remembered the feeling I had on seeing Christopher Nolan's low-budget black-and-white debut, Following. Here is a director who is going places.

The drama concerns a shy, spindly, bespectacled young man called Parker Sithole, played by Mothusi Magano. He has an enigmatic, stricken look – like Jack Nance in Eraserhead or Anthony Perkins in Psycho. Parker is new in town, having turned up to take a job teaching English literature in a high school: we see him earnestly preparing lessons on Keats and Shakespeare. He is, as his headteacher puts it, "of good report", with a great degree result and fine references. But his landlady (Nomhlé Nkyonyeni) doesn't trust this quiet, secretive new tenant, and Parker's male colleague, a boozy reprobate called Vuyani (Tshamano Sebe) recognises a strange darkness in him. Parker is troubled by family memories and flashbacks to gruesome military service in the Democratic Republic of Congo, and his lethally non-mousy side is revealed when there is a spark of desire between him and a pert teenage girl in his class played by Petronella Tshuma. Her name is Nolitha: it can be misheard as "Lolita". Their affair unleashes a macabre spasm of sexual obsession and violence.

The atmosphere throughout is disturbing and strange: the monochrome cinematography conveys classic Hollywood noir, but also something otherworldly, or surreal, like something happening on another planet or underwater, and liable at any moment to lurch into the most bizarre black comedy. When Parker is prevailed upon to take tango lessons with the school's dance teacher, Squeeza (Thobi Mkhwanazi) – who seems incidentally to have a bit of a crush on him — Qubeka conjures a fantasy sequence, like something from the musical Chicago, which dramatises Parker's clenched, nervous hysteria. There is an extravagant suspense scene in the girls' school lavatories and a delicious near-miss for Parker late on – both scenes of which Hitchcock might have approved.

The grim outcome of his affair with Nolitha triggers a traumatised flashback memory to the DRC, and a certain stumble on a bridge at night-time carries Parker back, like a Proustian madeleine, to a horribly embarrassing moment in his graduation ceremony. Qubeka cleverly and repeatedly brings in the two aspects of Parker's personality that don't exactly fit the banal stereotype of the teacher-perv. One is that he is someone of genuinely high academic promise (which perhaps puts him closer to Nabokov's refined Humbert Humbert) and the other is that he has seen some tough military service, apparently with a UN force. Was the military a failed career decision for Parker? Did his intellectual seriousness at some stage find expression in a need to serve in the armed forces, a life decision that came to a terrible end? We never discover anything about the beginning, middle or end of his military identity, other than fragments of horror, which in turn blend with the terrible family secret he carries with him. It is an enigma that radiates fear into every corner of the film. It's edge-of-the-seat stuff.

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