“The only poetry,” Socrates argues in Plato’s The Republic, “that should be allowed in a state is hymns to the gods and paeans in praise of good men.” Ezra Pound’s The Cantos contains numerous hymns to the classical gods, and much praise of good men. The problem facing the United States (of which Pound always remained a citizen despite his many years in Europe) was that prominent among the good men praised in his sprawling modernist epic was the leader of a country on which the US had declared war: Mussolini.

Still, contrary to Plato, poets rarely present much of a threat to the governments of western democracies, and Pound would probably have evaded the attentions of the US authorities had he not delivered on Rome Radio at the height of the second world war a series of broadcasts that were openly treasonous. In these he savagely denounced Roosevelt and Churchill and commended Hitler for “having seen the Jew puke in the German democracy”.

On his arrest in May 1945, the 60‑year-old Pound was dispatched by the US military authorities to a disciplinary training camp near Pisa. Initially he was imprisoned in a 6ft by 6ft steel cage, open to the elements. This was a traumatising experience, but may also have played a part in saving his life. After a few weeks he suffered a breakdown; psychiatrists examined him, and recommended that he be moved at once from his “gorilla cage”. In November he was transferred to Washington and arraigned for treason. The case against him was strong, but his mental breakdown furnished a loophole grasped at by all with relief. It would have been awkward for the US to hang one of its best-known poets, and although Pound would have undoubtedly enjoyed expounding his views in court, the risk of a guilty verdict was high. A plea of insanity was accepted on skimpy evidence, and il miglior fabbro – “the finer craftsman”, as TS Eliot called him – spent the next 12 years in St Elizabeths Hospital on the outskirts of Washington, or “the bughouse” as Pound semi-affectionately referred to it.

Daniel Swift has had the bright idea of writing a book about Pound’s years in “the house of Bedlam”, to borrow a phrase from Elizabeth Bishop’s brilliant poem, “Visits to St Elizabeths”, which adapts the nursery rhyme “The House that Jack Built” to refract the craziness of Pound’s life and views and situation. The adjectives that her poem applies to Pound – tragic, talkative, brave, cranky, cruel, tedious, wretched – capture the spectrum of responses that he evoked in his many visitors. Along with such illustrious poets as Charles Olson, William Carlos Williams, Eliot, Robert Lowell, Bishop and John Berryman, they included a range of unsavoury white supremacists and antisemites. Pound thought of himself as “granpaw” to far-right fanatics such as John Kasper (who was jailed in 1957 for violent pro-segregation activities) and the crazed conspiracy theorist Eustace Mullins, and he keenly urged them to disseminate their repellent views as widely as possible.

Pound also published, under various pseudonyms, a host of articles suggesting his own antisemitism was as rabid as ever; in a piece written in August 1956 he observes: “It is perfectly well known that the fuss about ‘de‑segregation’ in the United States has been started by Jews.” This book’s strongest parts are those presenting yet more evidence of Pound’s continuing commitment to fascist, or what are now called alt‑right, politics.

Swift is eager, however, not to be seen as just another Poundian. The Bughouse is one of those “the quest for” or “in search of” biographical studies, in which the author dramatises every step of the research and compositional process. He itemises what everyone he interviews is wearing and keeps us abreast of the weather on the days he visits this or that archive or library: “On a perfect spring break day I went to the National Archives in Washington”; “I began this book in a New York winter, in days as sharp as a new haircut … ”

It’s a genre, I confess, whose appeal I find mystifying. Why on earth should we care that Carter Wormeley, who shows Swift around St Elizabeths, is “wearing a dark suit and a white shirt, and by his car he takes off his jacket to show a pair of blue-and-yellow braces”? Is it really necessary to recreate the mundane experience of sitting in a reading room waiting for material ordered from an archive to arrive? “Each hour the files arrive in boxes on a squeaky cart from the vault beneath. The hush, the guards, the cart … ”. More irksome still are the numerous vignettes in which Swift presents himself in the act of reading Pound in different locales: “That evening I sat at a metal table outside a pizzeria on a sloping cobbled street in the town above the castle and ordered a carafe of red wine, and read the last cantos.”

Swift is himself an academic, and yet The Bughouse depicts other academics as if they belonged to some weird species with which he was wholly unfamiliar. The Pound scholars who assemble at the biennial international Pound conference are portrayed as “confused migratory birds”, and much fun is poked at their earnest expositions and disputes.

Swift also attends a session of the Ezra Pound reading group in Senate House, University of London. After the obligatory scene setting (“It is darkening outside in Bloomsbury and I walk quickly across the slip of marble, through art deco halls, past pale wood double swing doors”) we are invited to join him in some genial derision of the group: “There are hearing aids, worn faces. The light is hard and bad … The men wear dark shirts and shiny jackets with sharp lapels.” A serious “young apostle” discusses “Canto 93”, some footnote-skirmishing follows, after which the Poundians go for pizza in the Bloomsbury dark. Swift pointedly does not accompany them. He is not one of their tribe: as that simile comparing a winter’s day in New York to a sharp new haircut so dramatically insists, he is a writer.

• The Bughouse is published by Harvill Secker. To order a copy for £25 (RRP £20) go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.