Lotte Lenya. The name conjures up visions of the Berlin Theatre Ensemble, of the plays of Bertolt Brecht and the music of Kurt Weill.

Or would you believe Joe Masteroff, John Kandor, and Fred Ebb? These three are responsible for the book, music, and lyrics to Cabaret, in which Miss Lenya struggles through turgid material of a sort usually left to the likes of Molly Picon.

Based on John Van Druten's play, I Am A Camera (based in turn on a series of stories by Christopher Isherwood), Cabaret is set in the Berlin of 1930, where a naive young American novelist meets up and shacks up with a degenerate English cabaret girl. Then their landlady gets engaged to a Jewish widower living in another apartment in the same building.

And that's the first act--90 minutes of tedious exposition, interrupted at nitervals by flashy cabaret numbers signifying nothing, plus two musical attempts to represent the unrest which will shortly usher in Nazism. Some of the scenes and some of the songs are briefly engaging, particularly the "Pineapple" number sung by Miss Lenya and Jack Gilford, and Jill Haworth's opening carabet song. But nothing jells. The book seems to have been written as padding for an inspired score, and the score as the same for an exceptional book.

The second act is better. Something happens in it. The landlady (Miss Lenya) decides not to marry her Jewish tenant (Mr. Gilford) because of the climate of anti-Semitism. The cabaret girl (Miss Haworth) refuses to leave Germany with the American writer (Bart Convy) and, thinking their relationship at an end, gets an abortion. There follows a melodramatic confession scene in which Miss Haworth broadly hints at what she has done, but scrupulously avoids the word for it. Mr. Convy zips off to Paris, Miss Haworth goes back to work, and Hitler comes to power, with all that that entails.

Only in the rare instances when something works do we get an idea of what Cabaret was meant to be. Joel Gray, as the master of ceremonies, does a brilliant love song with a female gorilla, titled "If You Could See Her Through My Eyes." The obvious parallel to Miss Lenya's relationship with Mr. Gilford gives the song a relevance all the other cabaret numbers lack. A song of popular unrest, "Tomorrow Belongs to Me," is later twisted into a grotesque Nazi rallying cry, and the meaning is again clear.

But more often the songs are like Mr. Convy's dreamy love ballad: standard, detached from the rest of the show, and unprovocative. Absurdly contrived stretches of transitory dialogue serve to get the audience away from the plot-line and into the song-line.

Cabaret's ambitions are loftier than those of most musicals: it attempts to sketch an era by playing a personal drama against a political one. But the attempt gets lost in a mire of timeless musical cliches, and we are left with a peculiarly ungripping love story.

Maybe Miss Lenya was brought in to lend the thing an air of Brechtian respectability. If so, it didn't work.