When South African shop assistant Eleanor Logan was arrested in August 1963 under the apartheid government’s 90-day detention laws, it shocked the genteel world of Durban bohemians she belonged to. A white single mother with parents well connected with South Africa’s artistic world, the secret police seized her from her workplace of Grigg’s Books under suspicion of being associated with the African National Congress’s (ANC) struggle against the white supremacist regime in Pretoria.

They didn’t quite know how right they were. Arrested mere weeks after the apartheid police had arrested Nelson Mandela and other ANC leaders, they picked up Eleanor hoping she would divulge the whereabouts of her boyfriend, Ronnie Kasrils, a communist anti-apartheid militant wanted in connection with the apparent sabotage of infrastructure across the region.

But far from a passive source of potential knowledge, Eleanor was active in the armed struggle. As one of the earliest recruits to uMkhonto we Sizwe (MK), the ANC’s armed wing, she had been involved in attacks on Special Branch offices, post offices and vital infrastructure. Utilising her naturally unassuming character, she served as a getaway driver, dynamite procurer, and courier for the underground until capture.

Upon her arrival at prison, it quickly became clear how police had discovered her. Not even a balaclava could disguise the face of someone she recognised as an MK fighter smoking cigarettes with the torturers of comrades who were now bleeding in cells. Declaring to the authorities her intention to go on hunger strike against her detention, she immediately plans to plot her escape from her brutish interrogators, who taunt her over her trust for this turncoat.

This moment in Eleanor’s life is the subject of The Unlikely Secret Agent, performing in London for the first time at the Marylebone Theatre from Wednesday 28 August to Sunday 1 September. Adapted with great sensitivity from Ronnie Kasrils’ award-winning biography of the same title, the play was developed as a concept during lockdown and has toured South Africa to much critical acclaim.

In Erika Breytenbach-Marais’ searing performance of Eleanor, her incarceration is captured in full intensity. Collectively bombarded by the repeated threat of ‘we’ll break you or hang you’ by agents performed by Ntlanhla Kutu, De Klerk Oelofse, Wessel Pretorius and Sanda Shandu, she withstands threats towards her and Ronnie, towards whom they demonstrate a psychotic, virulently antisemitic obsession, as well as agents threatening to disappear her daughter into forced adoption and acts of physical violence that are difficult to watch.

Yet Eleanor is uninterested in being broken. Feigning a mental breakdown, she is sent to a psychiatric institution, where she befriends a group of alcoholic women being sent to ‘dry out’ in a secure unit by their families. With the assistance of a Zulu woman working as a cleaner, she begins working out ways to possibly escape, alert the movement’s leadership about traitors in its midst – and to find Ronnie, moving through underground safehouses across the country.

In demonstrating the brutality of South African apartheid, The Unlikely Secret Agent succeeds. But it doesn’t simply document the worst; alongside scenes of Eleanor’s envelopment by torturers are matching moments of humour and life. Pretorious masterfully captures ‘Red’ Ronnie Kasrils’ combination of impishness and political commitment (from lampooning Eleanor attending Swan Lake to requesting copies of Che Guevara’s Guerrilla Warfare through her workplace), while moments of parties where Eleanor befriends radicals of all backgrounds show a human warmth that rivals the depravity of apartheid’s vanguard.

With a soundtrack covering The Chordettes’ Mr Sandman to Miriam Makeba’s Ndodemnyama (Beware, Verwoerd!), Unlikely Productions have produced a powerful work that pays real tribute to those willing to sacrifice everything to end apartheid. But it also highlights the deeply humane motives behind those heroics. The play’s mention of Che Guevara’s war writings documents an aspect of Eleanor Kasrils’ life of commitment. But watching the entirety of The Unlikely Secret Agent may make the viewer sooner remember Che’s quip that ‘at the risk of sounding ridiculous, the revolutionary is guided by feelings of great love’.