Summary of the musical Flora the Red Menace :
Flora Mezaros is a stubborn but hopeful young aspiring fashion illustrator. She is a member of a cooperative of artists who, like her, struggled to find work during the Great Depression. Flora lands the Holy Grail: a job at a department store for $30 a week. She falls in love with Harry Toukarian, a shy, stuttering designer. He tries all the same to convert Flora to her communist ideals. Charlotte, one of the party members (who has her sights set on Harry) points out that the store where Flora works is not unionized. Flora promises to collect the names of any employees interested in forming a union. Charlotte goes so far as to propose a gathering in front of the store where Harry will speak.
On D-Day, the rally looks more like a picket line. Flora understands that if she crosses the picket line, she will be expelled from the party. So she asks another employee to give her illustrations to her boss. But unfortunately, Flora realizes that she has submitted the list of employees wishing to unionize instead of her job. As Harry finally manages to speak and be listened to in front of the crowd, Flora crosses the picket line, sacrificing her relationship with Harry and her job in order to save those of the other employees she has endangered.
Find "Sing Happy", performed by Liza Minnelli. And yes, it's in the musical Flora the Red Menace that Liza Minnelli made her debut on Broadway and won her first Tony Award at 19!