NEW YORK — FALSETTOLAND Musical with music and lyrics by William Finn. Directed by James Lapine. At Playwrights Horizons. `FALSETTOLAND'' observes an instance of the consequences of homosexual relationships in an age of so-called sexual liberation. The context of William Finn's new musical is surprisingly lighthearted. But the mood grows darker as the composer-lyricist approaches the AIDS-determined finale of the brief work that concludes his trilogy.
The trilogy began with with ``In Trousers'' (1978) and continued with the highly successful ``March of the Falsettos.'' Employing a characteristically jaunty musical idiom, Mr. Finn recounted how his hero Marvin abandoned wife Trina and their son Jason for a male lover named Whizzer. Trina subsequently married Mendel, her ex-husband's psychiatrist. All are present and accounted for in the latest work.
``Falsettoland'' brings the situation forward to the eve of Jason's bar mitzvah. The circumstance permits Mr. Finn to philosophize and comment humorously on a wide range of ethnic and other matters. These extend from sports (notably Jewish boys and baseball), family relationships (``Everyone Hates His Parents''), role-playing, various kinds of domesticity, and young Jason's reactions to the immature adults who surround him.
Mr. Finn opts for a denouement which, in heterosexual surroundings, would be considered sheer sentimentality.
Under James Lapine's energetic direction, the Playwrights Horizons cast does everything possible to make a plausible case for the Finnian thesis. Since spectators' approaches are bound to be subjective, his degree of success may well lie in the eye of the beholder.
``Falsettoland'' is well-acted and strongly sung by Michael Rupert and Stephen Bogardus (Marvin and Whizzer), Faith Prince and Chip Zien (Trina and her marital replacement), Heather MacRae and Janet Metz (a pair of lesbian neighbors), and of course the indispensable Danny Gerard (the indispensable Jason).
The moral attitudes displayed amid the alien landscape are as mobile as the furnishings of Douglas Stein's 1980s setting (lighted by Nancy Schertler), with costumes by Franne Lee. The brisk musical performance is directed by arranger-pianist Michael Starobin.