Act I: March of the Falsettos
It is 1979 in New York City, and Marvin, his son Jason, his psychiatrist Mendel and his male lover Whizzer are "Four Jews In A Room Bitching". Marvin steps forward to explain his situation: He has left his wife, Trina, for Whizzer, but Marvin wants "A Tight-Knit Family" and is attempting to forge a new family situation with the addition of Whizzer, a situation no one is happy with.
Trina, on Marvin’s recommendation, pays a visit to Mendel where she wearily wonders how her life has turned out this way. Mendel, instantly attracted to her, tries to console her, telling her that "Love is Blind". Meanwhile, Marvin and Whizzer comment on their relationship. They have very little in common, apart from the fact that they both love fighting and are insanely attracted to each other. Both worry that "The Thrill of First Love" is wearing off.
The cast presents an interlude: "Marvin at the Psychiatrist, a Three-Part Mini-Opera." In part one, Mendel asks Marvin about his relationship with Whizzer and Marvin weighs the pros and cons of the relationship, ultimately concluding that he does love Whizzer. In part two, Mendel, obviously aroused, interrogates Marvin about his ex-wife's bedroom habits. In part three, Marvin and Jason provide counterpoint on their strained relationship.
Ten-year-old Jason is very worried that because "'My Father's a Homo'" he will turn out to be one too. His worries cause him to misbehave, and "Everyone tells Jason to see a Psychiatrist". Only on Whizzer's advice does Jason agree to see Mendel.
Marvin is trying to pigeon-hole Whizzer into the role of homemaker, and they fight. Meanwhile, Trina complains to Mendel how her role in the family is shrinking as Whizzer becomes increasingly prominent in Marvin and Jason's lives. All agree that "This Had Better Come To A Stop".
Despite her attempts to maintain a sense of normalcy, Trina's is spiraling out of control I'm Breaking Down. Jason continues to misbehave and Trina phones Mendel frantically to "Please Come To Our House" for dinner and therapy. Mendel arrives and immediately charms Trina. He and Jason settle down for "Jason's Therapy". Jason frets about his future and Mendel, in a very round-about way, encourages him to relax and enjoy life. After several such dinners combined with psychiatric sessions, Jason asks Mendel what his intentions are towards Trina. Mendel makes "A Marriage Proposal". Though clumsy and neurotic, he's sincere and Trina accepts his offer. Marvin is furious that he is losing his "Tight-Knit Family (Reprise)" as well as his therapist.
In "Trina's Song", she reflects on her situation. She is tired of the man's world she lives in, and even though she knows that Mendel is the same kind of man Marvin is, slightly childish and neurotic, he loves her and she could do a lot worse. In contrast, the four men sing a hymn to all varieties of masculinity, with the three adults singing in falsetto to match Jason's voice March of the Falsettos.
Marvin teaches Whizzer to play chess, but bitterness and ill-feeling boil over The Chess Game. They fight and break up. Meanwhile, Trina and Mendel move in together and start "Making a Home". As he packs, Whizzer reflects on "The Games I Play" with his own heart and comes to the conclusion that he does not love Marvin.
Trina and Mendel send out wedding invitations, and Marvin goes crazy. He confronts Trina and incoherently accuses her of trying to ruin his life, finally breaking down in rage and slapping her. Shocked by his actions, both reflect that "I Never Wanted To Love You", a sentiment Whizzer repeats to Marvin and Marvin repeats to Jason and Whizzer.
Marvin is finished with Whizzer, and his relationship with Trina is in tatters, but Marvin can still salvage his relationship with Jason, who has just discovered women to his immense relief. Marvin sits down Jason for a talk "Father to Son" and tells him that he loves him, and no matter what kind of man Jason turns out to be, Marvin will always be there for him.
Act II: Falsettoland
Mendel shines a flashlight into the audience on a dark stage, welcoming us to "Falsettoland," the story's conclusion. It is 1981, two years later. Nancy Reagan is in the White House, and the cast has been enlarged by two, Marvin's Lesbian neighbors Dr. Charlotte, an internist, and Cordelia, a kosher caterer. Marvin has realized that it's "About Time" to grow up and get over himself. He has called a truce with Trina, and he has managed to maintain his relationship with Jason, who is now preparing for his Bar Mitzvah. He has not seen Whizzer for two years, and has still not gotten over him.
One day, when she arrives to take custody of Jason for the week, Trina informs Marvin that it is time to start planning Jason's Bar Mitzvah, probably the last pleasant thing the ex-couple will do together. The pair immediately start bickering to Jason's dismay and Mendel's amusement. Mendel encourages them to have a simple party, but Trina (and Cordelia, the caterer) will have none of it. It is "the Year of the Child", after all, the year that every Jewish parent dreams of: the year their child is bar mitzvahed and they can spend insane amounts of money celebrating.
The scene moves to Jason's Little League Baseball game. While at bat, Jason has a lot more on his mind than the game. He is trying to decide which girls to invite to his bar mitzvah: the girls he should invite, or the girls he wants to invite. Reaching a decision would be a "Miracle of Judaism." Everyone is there at "The Ball Game." Everyone is sitting watching Jewish boys who can't play baseball play baseball and getting a little too involved in it, when Whizzer suddenly arrives. Jason had asked him to come. Marvin is struck by how little he's aged, and a tentative offer of reconciliation is made just as Jason manages to hit the ball. He is so shocked he forgets to run.
An interlude: "A Day in Falsettoland." In part one, "Dr. Mendel at Work," Mendel listens to the blather of a yuppie patient and agonizes about being a sixties shrink stuck in the eighties and how his work is taking a toll on his marriage to Trina. In part two, "Trina Works It Out", Trina reveals Marvin and Whizzer are back together and wonders why that troubles her. In part three, "The Neighbors Relax", Mendel and Trina jog and discuss Marvin and the Bar Mitzvah, and Dr. Charlotte comes home to Cordelia cooking "nouvelle bar mitzvah cuisine." Cordelia asks Charlotte how her day was at the hospital, and Charlotte exclaims that today was a rare day without a death. Meanwhile, Marvin and Whizzer play racquetball and bicker when Whizzer beats Marvin soundly. All reflect on how wonderful life is.
The peace does not last long. Marvin and Trina are warring over every aspect of the Bar Mitzvah, which makes Jason want to call it off. Mendel consoles the boy, telling him that "Everyone hates his Parents" at his age, but everyone also matures and hates them less.
Marvin sits in bed one morning, looking at the sleeping Whizzer. "'What More Can I Say?'" he asks, wondering at how much he loves him. Dr. Charlotte, meanwhile is becoming aware that "Something Bad is Happening" among young gay men in the city, who arrive at the hospital sick with a mysterious illness that no one understands. Rumors are spreading, but the disease is spreading faster. Then Whizzer collapses during a game of racquetball.
Whizzer enters the hospital, and Trina is disturbed to find how upset she is at his condition. She is barely "Holding to the Ground."
In Whizzer's hospital room, the entire cast gathers to cheer him up. Everyone commenting on how well he looks. Marvin provides love, Cordelia chicken soup, and Mendel some terrible jokes. Everyone agrees that is it "Days Like This" that make these secular Jews believe in God. Only Jason, in childish honesty, is able to tell Whizzer the truth: that he looks awful.
Mendel and Trina sit Jason down and give Jason the option of "Canceling the Bar Mitzvah" if he feels he can not go through with it. Jason finally learns that Whizzer may not recover. Marvin sits in Whizzer's hospital room, soon joined by Cordelia and Dr. Charlotte, and the four "Unlikely Lovers" wonder how much longer their love can last.
As Whizzer's condition worsens, Jason turns to God, asking him to perform another "Miracle of Judaism" by allowing Whizzer to recover. He will even get Bar Mitzvahed if Whizzer gets better. Then Dr. Charlotte reiterates that "Something Bad is Happening." Whizzer is soon near death, and he reflects bravely that "You Gotta Die Sometime."
Suddenly everyone bursts into the hospital room. Jason has had an epiphany: he wants to hold "The Bar Mitzvah" in Whizzer's hospital room. Trina could not be prouder. Everyone notices how much Jason looks like Marvin. Jason becomes Bar Mitzvah. Whizzer can suddenly bear no more of their company and is taken from the room, followed by all but Marvin.
Marvin, left alone, asks the departed Whizzer "'What Would I Do' if you had not been my friend?" Whizzer appears, dressed as we first saw him, and the two sing together one last time. They realize that there can be no answer to Marvin's question -- but the question remains. Then Whizzer is gone.
Marvin's friends and family surround him, as Mendel bids the audience goodnight from the world known as "Falsettoland."