What a revelation for my uninitiated ears Kurt Weill's Street Scene proved to be in Opera Group's valiant production. There is nothing quite like this fascinating hybrid of opera and Broadway musical, which premiered in the late Forties and has undeservedly languished in obscurity ever since.

Weill's evocation of family and communal life one heat-wave, summer season in a downtown New York tenement concentrates upon risky sexual desire and adulterous yearnings that rise in the steamy heat of several bodies. The spirit of Tennessee Williams is summoned, though Elmer Rice wrote the original play in the Twenties.

The nervy, exultant music, as the orchestra's heartfelt performance keeps reminding us, abounds with faint echoes of Stravinsky and Richard Strauss. The composer incorporated jazz early in his career, but Weill's score also absorbs what were for him the fresher influences of the blues, negro spirituals and Broadway show tunes of the Rodgers and Hammerstein genre.

The idea, as radical in its way as Gershwin's Porgy and Bess and wider in its scope ,was to create a kaleidoscope of working-class and immigrant tenement people, the prime focus being on a single family rent asunder.

Ranging from spoken to sung episodes, Street Scene embraces Puccini-like love duets and big Broadway choruses. Sex is not just in the air, it feels as if it's in the water, too. Against a backcloth of gossiping neighbours who pry and peer, middle-aged Anna Maurrant's adultery with the collector for the local milk runs a fatal course, the music rising to a violent outburst as dramatic as the murder scene in Strauss's Electra.

Elena Ferrari, oddly artificial, cold and winsome as Anna, forever at the mercy of the superb Andrew Slater as her suspicious, angry-bull, anti-Semitic husband, is one of the performers who betrays the crucial weakness of John Fulljames's production: the orchestral sound is too loud. It muffles many singers to the extent that supertitles are needed.

The imbalance between orchestra and singers similarly affects Ruby Hughes as Anna's attractive daughter, Rose, warding off unwelcome male advances, and Adrian Dwyer's geekish, Jewish young man, Sam, for whom she languishes. Fulljames, though, ensures the dramatic impact of this opera-musical scarcely falters.

A huge ensemble, some standing above a stage equipped with two staircases, thrillingly registers the climactic moments of an extraordinary opera-musical that deserves further exposure.
Until 22 July (020 7922 2922)