Political theatre isn’t just about depicting reality and expecting the audience to interpret it, coldly and rationally, as a call to some political action. That’s what Bertolt Brecht seemed to think anyway. “Political theatre,” he wrote, “must stimulate a desire for understanding, a delight in changing reality. Our audience must experience not only the ways to free Prometheus, but be schooled in the very desire to free him.” Even at its most impassioned, its most didactic, Brecht’s drama is an aesthetic experience, and an emotional one too.

Watching the production of Aimé Césaire’s ‘A Season in the Congo’ (Une Saison au Congo) at the Young Vic theatre in London, I couldn’t stop thinking of Brecht. This incredibly rich, subtle and moving play depicts the last couple of years of the life of Patrice Lumumba; mostly concentrating on his short time as Prime Minister and the circumstances (much disputed) leading to his death. Lumumba is played by Chiwetel Ejiofor, a British actor born in London to Nigerian parents.

The story of Lumumba told onstage ends in the same way as it did in real life; though most of the attention is on the Congolese context and the machinations of President Kasa-Vubu and Colonel Mobutu. Further upstage on a raised platform, European and American bankers scheme in the background, represented by grotesque caricatured puppets, that to my mind recalled the figures of Hitler and his generals in Brecht’s ‘Schweik in the Second World War’. On the same part of the stage Lumumba goes to the UN Secretary-General Dag Hammarskjöld and disembodied heads representing the USSR and USA argue with each other over the theatre floor. Down below, some of the audience sit at small tables and outside furniture, set up to look like a bar in Leopoldville (Kinshasa), drawing us in to the action and evoking the life of the Congolese capital at the epoch of independence. The staging is constantly inventive; towards the end, a long table of people, greedily eating their fill like the top table at a wedding, suddenly stand up and become the firing squad that executes Lumumba.

When Belgian paratroopers drop on Katanga province an actor walks across the stage carrying a model plane and the theatre is filled with the sound of its engines. Small objects – I guess toy soldiers – drop from above attached to paper parachutes. Perhaps my description doesn’t do it justice, but the effect on the audience is to feel a sudden shifting of perspective, so that one is not simply observing Leopoldville, one is there, one is “schooled in the desire”, as Brecht would say, to see Congo free of Belgian influence.

These effects of props, models, lighting, staging, sound, and movement constantly give one this sense. Sometimes director Joe Wright shows you into a nightclub in Leopoldville, sometimes suspending you over the entire city or the entire country while vultures (puppets manipulated by the cast) ready themselves to pick over Lumumba’s corpse.

Césaire’s language is beautiful; he has an amazing ability to slip between tones and registers, introducing moments of poetry into the characters’ speech. Most of these lines go to Lumumba, and Ejiofor (whose performance, incidentally, is brilliant) has the right intensity and personality to carry off the act, switching lightly between persuasion, anger, humour, seduction, doubt and introspection. At one moment, Lumumba is imploring his close friend Mokutu to understand the importance of liberation politics to the continent. He holds out his right hand, flat, fingers together, and invites the other man to look: “Do you ever think about Africa? Look here. No need for a map hanging on the wall – it’s written on the palm of my hand.”

That’s the kind of image that comes alive when you hear it spoken, that impresses itself into your mind and achieves the same effect that the planes and paratroopers did earlier. In the dark of the theatre, I held out my hand in front of me, low down in my seat, arched my thumb out to make West Africa, wiggled my fingers for Cape Agulhas, and imagined the lines on my palm making the Congo River.

• ‘A Season in the Congo’ runs until 24 August at the Young Vic. Here’s the trailer.