Contrary to the conclusion of Act Two when Arkadina decides to stay, Act Three begins with Trigorin eating lunch in Sorin's dining room, surrounded by packed luggage. It appears that they are leaving afterall. Masha keeps Trigorin company, confessing her plan to marry Medvedenko She says that it will rid her of her love for Treplev not because she will love Medvedenko, but because marriage will keep her busy and give her responsibilities. Masha asks Trigorin to convince Arkadina to stay longer. Boris Trigorin responds with the information that Treplev's recent injury as a result of trying to shoot himself in the head and Treplev's recent challenge to Trigorin to fight him in a duel has caused Arkadina's change of mind and decision to take Trigorin away from the estate. Masha sums up Treplev's troubles by concluding that he is jealous. She goes on to talk about herself. She leaves after asking Trigorin to sign one of his books for her with the inscription, "For Masha, who doesn't know where she came from or why she goes on living."
Nina enters and asks Trigorin to play a game with her that involves a pebble in her hand to predict whether or not she'll become an actress. Trigorin warns her that no one can predict something like that about one's life. Nina gives Trigorin a gift of a medallion with his initials inscribed on one side and the title of his book, "Days and Nights" on the other. She asks him to give her two minutes more before he leaves.
Arkadina observes that Trigorin and Nina had a private conversation. She snidely remarks that she hopes she "didn't interrupt anything." Trigorin discovers that also inscribed on the medallion is a page and line number from his book, "Days and Nights". He goes off-stage to find the book in order to read the quote to which Nina's gift refers while Arkadina argues with her brother, Sorin about joining them in town. Arkadina genuinely worries about Sorin's health. Sorin's boredom and restless nature cause him to desire to go back to Moscow with Arkadina and Trigorin. Arkadina insists that Sorin stays on the estate to keep an eye on Treplev, who is in an unstable mental condition.
Sorin reluctantly, but firmly, explains to Arkadina that Treplev's pride was damaged by the lack of compassion she displayed for his play. He describes how a man like Treplev needs to feel appreciated. Sorin describes to Arkadina how Treplev's vulnerable ego needs tenderness and mercy as he struggles to find his artistic voice. Unsympathetic, Arkadina exclaims that Treplev only causes her trouble and questions why he does not get an office job. Sorin asks Arkadina if she would lend Treplev some money. Sorin believes this would bring some peace to Treplev, who needs a new winter coat and would benefit from a few luxuries. At first, she balks at this idea and cries poor, but later, she admits that she does have some money. Sorin falls ill for a few moments and Arkadina becomes frightened. She screams for help.
A humorous and swift device of propelling the sense of time into the future, conveying to the audience that action has occurred and time has passed, Chekhov's stage directions for surrounding Trigorin in packed luggage at the beginning of Act Three is a marvelous and efficient detail. Act Three opens up with a conversation between Trigorin and Masha that reiterates the existential theme running through The Seagull and brings this theme to focus. A Chekhovian gesture, one where our expectations are reversed, exists in the attention to the packed suitcases. Arkadina announces her decision to stay at the end of Act Two, but these bags prove that since the close of that act, time has passed and her decision has changed. As in real life when events or emotions turn on a dime, transforming a funny moment into a mournful one, or a triumphant moment into an embarrassing one, Chekhov portrays the way our uncertain fates always have the last laugh on our lives.
Like Sorin, Masha gets through her monotonous days by keeping herself busy with the mundane in life, not by pursuing intellectual or creative dreams. Masha's reason for marrying Medvedenko is to forget her unrequited love for Treplev. However, Masha does not marry for love or financial necessity, but to get through life with some sense of meaning. She exhibits a no-nonsense, melancholy form of awareness, and she truly attempts to understand Treplev and admires his attempt at greatness. When others find him perplexing, Masha observes quickly that Treplev is "jealous" or "depressed." In her request to Trigorin for an inscription in her book that he wrote, she asks for him to refrain from writing "best wishes or anything like that." Masha does not believe in false sentiments. She explicitly requests Trigorin to write, "For Masha, who doesn't know where she came from or why she goes on living." With this request, Masha describes herself knowingly in the state of an existential crisis. Without Treplev loving her in return, Masha finds it hard to understand why she was meant to live if her life is not working out to make her happiest.
Existentialism is a conundrum many Chekhovian characters face. In The Seagull, Sorin and Treplev also grapple with questions about the meaning and purpose of their seemingly futile existence. In Chekhov's last play, The Cherry Orchard, a German governess, Charlotta, repeats almost verbatim Masha's sentiments. Adopted and without a passport, Charlotta says, "I don't know who I am. I don't know where I came from." Chekhov manages to portray the absurdity of life's meaninglessness on stage. Characters like Masha and Charlotta grapple with existential questions and cannot answer them, to their dismay. However, in gloomy Masha's case, we can laugh at her excessive melancholy, thereby, laughing at our own, unsolvable predicament.