Act I
In an elegant salon in her house in Montmartre, the courtesan Magda entertains her guests, including the fashionable poet Prunier. Lisette, the host’s maid, annoys Prunier with her over-friendliness; they are having a secret affair and he has promised to make her into a famous actress. Magda, who is the lover of the wealthy banker Rambaldo Fernandez, reminisces about a time in her youth when she was madly in love with a student. She sings a song composed by Prunier and improvises the ending, much to everyone’s delight, including Rambaldo’s. Magda is interested by something that Prunier said – that real love, faithfulness to one person, is in vogue again. The others receive this with sarcastic remarks. Prunier offers to read the ladies’ fortunes. It’s simple – everything is written on each of their palms.
Lisette tells Rambaldo that there is a young man that has been waiting for him for a few hours. It is Ruggero, the son of one of Rambaldo’s childhood friends, who has arrived from the provinces. Magda is pleasantly surprised by the youth’s manners and shyness. Prunier notices this and, continuing his palm-reading, foresees that Magda, like a swallow, will fly towards her dreams for a while, but eventually, not having reached her goal, she will return to her old life.
Rambaldo asks the guests to give Ruggero suggestions for where to spend an evening out in Paris. Lisette suggests a fashionable nightspot called Bullier. She is also planning to go there tonight with Prunier. Ruggero, slightly bewildered by the raucous bunch, says his goodbyes and leaves. Beguiled by Ruggero, Magda decides to disguise herself and meet him tonight at Bullier.
Act II
The bar at Bullier is full with the buzz of revelry. Ruggero sits by himself and observes the goings-on. Courtesans vie for the attention of young men. Magda arrives and is immediately surrounded by students, but she convinces them that she already has a seat at Ruggero’s table. Ruggero, surprised and puzzled, invites her to join him. The young man is attracted by her shyness and grace. They go to dance. During their conversation Magda doesn’t reveal her true name, instead calling herself Paulette. Both are overcome with feelings of love, which even the unexpected arrival of Lisette and Prunier cannot quell. It is also not in Rambaldo’s powers to quell when, as the friends have pulled Ruggero aside, Magda explains to Rambaldo that she is refusing his guardianship because she wishes to follow her new, true love. Overjoyed, the lovers leave the bar.
Act III
Magda and Ruggero, overcome with bliss, are staying at a quiet resort on the French Riviera. They are happy. Ruggero has decided that Magda must become his bride. He has secretly written to his parents of his plan and has asked for their permission to marry. When she learns of this, Magda realises that she has gone too far, and that she cannot hide from her past any longer. Her conscience won’t allow her to set foot in Ruggero’s parent’s house. Magda decides to sacrifice her love and leave Ruggero. Prunier’s prophecy has come true. Lisette has had a disastrous debut on stage, and she wishes to work for Magda again as a maid.
Ruggero rushes in with a letter from his mother. Magda reads it and is deeply moved – Ruggero’s mother consents to the wedding. Yet Magda cannot accept the proposal. She reveals to Ruggero everything about her past and, parting with her one true love for good, she returns to Rambaldo.