There is an apocryphal story that when asked by US diplomat Henry Kissinger in 1972 what he thought was the impact of the French Revolution, the Chinese premier Zhou Enlai replied that it was too early to say. It’s a quote that has become a legend, flattering Western preconceptions about taciturn, patient Eastern wisdom as well as the propensity of the Chinese Communist Party towards long-term planning.

In reality, the truth was lost in translation. Zhou had assumed that Kissinger was referring to the 1968 insurrection by workers and students, and not the revolution of 1789. Nonetheless, the longevity of the line comes down to its deep truthiness: whether or not he intended it that way, it suggested that the impact of revolutions can only be understood through a very long view. Conventional written histories often adhere to this same logic, with subtitles bearing dates that stretch over years, decades, even a century.

In his new book Hotel Lux: An Intimate History of Communism’s Forgotten Radicals, the Irish historian Maurice J. Casey inverts the logic of history’s grand narratives and opts instead to illuminate the revolution and its consequences through small stories. The radical promise of Russian communism, the feverish decade of labour by its organisers and bureaucrats to secure its success, and its eventual betrayal by a metastasising Stalinist paranoia all feature not as the main narrative but as a backdrop for a compelling untold drama: that of a small group of international communist activists who moved to Moscow to work for the Comintern.

The Comintern was an international organisation led by the Soviets to advocate and organise for communist revolutions, in the Russian model, across the globe, and many of its international workers were housed in a rapidly crumbling former hotel in the centre of Moscow, the Hotel Lux, which became a hothouse for revolutionary theorising, sexual and romantic intrigue, and, perhaps inevitably, internecine sectarian plotting.

At the centre of this circle of revolutionaries, who hailed from Germany, the United States, the United Kingdom, and Ireland, is May O’Callaghan, a journalist, editor, and translator from a rural coastal village in Wexford. Born in 1881, O’Callaghan already had a formidable political career to draw from when she travelled to Moscow in 1924. As a young woman she had left her home to study in Vienna, before moving to London on the eve of the First World War to take a job working for the Woman’s Dreadnought, a feminist journal published by the suffragette Sylvia Pankhurst. As Pankhurst moved further left, embracing working-class struggles, the paper became the Workers’ Dreadnought, a hub for radical voices, including Irish nationalists and anti-imperialists from across the empire. Through her work at the paper, May met Rose and Nellie Cohen, two Jewish sisters from East London some ten years her junior. All three would eventually end up in the Lux, alongside Irish revolutionary and author Liam O’Flaherty, also a Dreadnought correspondent; Emmy Leonard, a former parliamentarian of the Social Democratic Party of Germany (SPD), radicalised by the German Revolution; Hugo Rathbone, son of a Liberal MP; and Joseph Freeman, an American communist writer who had fled his native Ukraine as a child to escape antisemitic pogroms. They are joined by an astonishing cast of cameos: Maxim Gorky, M. N. Roy, Frida Kahlo, Claude McKay, Boris Pasternak, and Simone Weil all appear, bit actors in the lives of our own private circle of comrades.

One might be tempted to call May a mother to this disparate group of young radicals, had their attitude towards rethinking and revolutionising sexual and gender norms not been such an important engine in their personal lives. Nevertheless, her experience and wisdom certainly made her a trusted confidant to many, and this puts her story at the centre of Casey’s history. The book is deeply intimate. Reconstructed through official and informal archives ranging from secret personnel files in the Russian State Archive in Moscow to bin bags of love letters found mouldering in a Spanish outhouse, Casey’s book focuses on how his subjects felt about the revolutionary epoch they found themselves in, and how they felt about their comrades. It’s a book about the effect of love upon politics, and of politics upon love. Through their collective struggle they each come to understand what the others have invested in revolution; they debate and argue; they care for each other and abandon each other; they have sex and they have children. In one letter, May chastises a comrade for how callously he treats the women he sleeps with, all under the guise of free love; questions whether new Soviet models for family life are in women’s interests; and dwells on how the sexual ethics of her own upbringing in Ireland have restricted her own desires.

For some historians, the archives are merely a catalogue of documents to validate or disprove their arguments. For Casey, they are a living source of meaning, and his joy in discovering connections and stories is contagious. Perhaps the most touching parts of the book are where he uncovers the archival traces of the children of this cohort of radicals — in the hand-drawn newspaper written in exile fortnightly by Emmy’s children for their father, the Dutch trade unionist Edo Fimmen, combining their precocious anti-fascist analysis with news of their pets; or in the burgeoning queer love story told by the letters between Emmy and Nellie’s daughter, overseen with discreet tenderness by May.

Hotel Lux is an unexpected treasure, unveiling the power of the archive to reanimate history and its complexities. In other hands, the telling of how the enthusiasm and energy of his subjects’ revolutionary fervour soured as it became subsumed into the cataclysmic paranoia of the Stalinist purges might have lent the story a grim, inevitable narrative motor. What is astonishing is how Casey’s archival approach prevents this. By bonding us to his subjects through their personal stories, he allows us to think empathetically through them, helping us understand how the Great Purge ‘became grimly intelligible to those compelled to live through it’ and why they made the choices they did. It forces us to ask ourselves the same questions: at what point would we have left?

Perhaps, most compellingly, by explaining these world-historical events through the personal relationships of intellectual sparring partners, lovers, and comrades, he demonstrates how exactly these productive, generative, intimate networks of friends which made the revolution so powerful also became the vectors along which Stalin’s paranoia and terror sped. Through actively caring for your friends, counselling them, writing them letters, you could be inadvertently condemning them, or yourself, to a speedy show trial and unceremonious execution.