292 pages, 244 x 170mm, with figures and music examples. Published by Cambridge University Press in the Music since 1900 series, paperback. Zagreb, June 1961. On the programme: Karlheinz Stockhausen, Pierre Schaeffer, Mauricio Kagel, Witold Lutosławski, the Darmstadt serialists, the tape pieces coming out of Paris, Milan and Cologne, and the experiments of John Cage. In a communist country that had spent the previous fifteen years under socialist realism, with closed borders and almost no contact with the outside. The following year Igor Stravinsky and Cage attended in person, alongside David Tudor, Luigi Nono, Luciano Berio, Bruno Maderna, Krzysztof Penderecki and Luc Ferrari. Several Yugoslav composers in the audience never wrote the same way again. A few stopped writing altogether.

How that happened is one of the stranger stories in Cold War music, and Laura Emmery's Yugoslav Avant-Garde Music, 1945-1991 is the first book in English to tell it properly. The Music Biennale Zagreb was engineered by composer Milko Kelemen, who had refused to bend to socialist realism, got himself out to Paris, Freiburg and Darmstadt, and then played the Soviets, the Americans and the Western Europeans against each other with invented stories about who else was coming. It worked. His festival became one of the most consequential contemporary music events in Europe for three decades.

The precondition for all of it was Yugoslavia's position after 1948, when Josip Broz Tito broke with Joseph Stalin and pulled the country out of the Eastern Bloc. Neither East nor West, with its own model of self-managed socialism, the federation discovered that experimental art was a currency it could spend abroad. The Communist Party paid for the festivals. Emmery draws out the full irony: a state that forbade its artists from expressing ethnic or religious identity, and which for years treated the avant-garde as Western decadence, ended up bankrolling one of the most active experimental scenes on either side of the divide.

For anyone who has chased the Belgrade electronic records, the middle section of the book is the reason to buy it. Emmery reconstructs the founding of the Electronic Studio of the Third Program of Radio Belgrade in 1972, built by Vladan Radovanović after his training at the Polish Radio Experimental Studio in Warsaw, and the acquisition of its Synthi 100, the custom instrument designed by Peter Zinovieff and David Cockerell at EMS in London. Told largely through Radovanović's own recollections and those of the composers who worked there, it is the first detailed account of how that room came together and what came out of it. Alongside him stands Ludmila Frajt, the first woman in Yugoslavia to work in electronic and film music, whose pieces run Yugoslav vocal folk practice - dissonant seconds, microtonal clusters, untempered heterophony - straight through techniques absorbed from Lutosławski, Penderecki and György Ligeti.

Then Belgrade in the 1970s. After the student protests of 1968, the Party handed the students a building in the city centre; the Student Cultural Center opened in 1971 and became the epicentre of the New Art Practice, the home of Marina Abramović and the Belgrade Six. Composers expelled from the Faculty of Music for writing minimalist and experimental pieces found a room there. Milimir Drašković, Miodrag Lazarov Pashu, Miroslav Savić and Vladimir Tošić formed Opus 4; Miloš Raičković assembled the Ensemble for Different New Music. They translated the texts, ran the listening sessions, put on the concerts, published the records. Emmery's chapters on the SKC are built from the archive and from interviews with the people who were there.

What keeps this from being a nationalist rescue operation is that Emmery is willing to report the bad reviews. She quotes Ulrich Dibelius writing off the Yugoslav composers as incapable of innovation, and concedes that for much of the 1960s the local scene was simply behind. Her argument is more interesting than special pleading: that in a state where socialist realism made even a polychord a political act, the measure of the avant-garde has to be internal, and that judged against the room it was made in, this music was genuinely radical. Elsewhere she is precise about what was world-class - Radovanović's stochastic computer work at Utrecht in 1977, Ljubica Marić's Byzantine modernism, Ivana Stefanović's radiophonic pieces, Ivo Malec's concrete music once he had left for Pierre Schaeffer's Paris.

The last chapters hurt. The Faculty of Music finally opened a computer studio in 1986 and had Macintosh IIs by 1988, among the first in Europe. The Magnificent Seven, seven young composer-performers crossing Yugoslav folk and rock with pop, jazz and musical theatre, emerged in 1988. Three years later the wars began, the studios went dark, the sanctions came, and six of the seven left the country. The epilogue is simply titled 1991.

Emmery, Associate Professor at Emory University and co-author of The Origins of Yugoslav Musical Minimalism, spent years in collections nobody had opened, working in a literature almost entirely written in Serbo-Croatian and long since fragmented among successor states with reasons to look away from it. This is that material in English for the first time, with photographs, personal papers and testimony from people now gone. If you own the Belgrade electronic reissues and have wondered what was actually going on around them, this is the missing context. Indispensable.