Scene 1
It is Martin's 50th birthday. In his suburban living room, he and his wife Stevie prepare to be interviewed on television by their friend Ross. Martin seems distracted and cannot remember anything. Stevie casually asks Martin about a woman's business card in his pocket and his odd scent. Martin denies having an affair with a woman, but confesses to falling in love with a goat named Sylvia. Stevie laughs it off, thinking it is a joke. Stevie leaves when Ross arrives. Ross begins interviewing Martin, congratulating him for being the youngest man ever to win the Pritzker Prize and recently being chosen to design a multi-billion-dollar city. However, Ross soon becomes frustrated with Martin’s inability to concentrate on the interview. Martin confides that the reason for his absent-mindedness is his affair with Sylvia, which began during his search for a country home. Amazed that Martin could fall in love with anyone but Stevie, Ross asks repeatedly, "Who is Sylvia?" Martin reveals a photo of Sylvia and Ross screams that Sylvia is a goat.
Scene 2
Ross has written Stevie a letter regarding Martin's affair and Sylvia's identity. Stevie confronts Martin about this, with their son Billy also in the room. Billy is shocked and flees (throughout this scene, he enters and exits sporadically). Stevie recounts the normalcy of her life before she opened Ross's letter. She realizes that Martin was telling the truth in Scene 1 and that she was right to worry about the business card and the odd scent. The card belongs to a member of a support group for bestiality. Martin claims that people like him seek animal company as a coping mechanism. For him, Sylvia is not just an animal; she has a soul and reciprocates his love. As Martin tries to justify himself, Stevie breaks various objects and overturns furniture. Finally, she exits, vowing revenge.
Scene 3
Billy enters the ruined living room where Martin remains. Billy claims that Martin and Stevie are good people and are better than most of his classmates' parents. However, he begins crying once he realizes that Martin's bestiality has torn their once happy family apart beyond repair.
Overwhelmed with a sense of loss and love for his father, Billy embraces Martin and kisses him sexually on the mouth. Martin pushes Billy away just as Ross enters to witness the scene. Martin angrily defends both his son and himself. Ross says he received a call from Stevie saying Martin needed him. Ross and Martin spar over Ross's letter and how Martin's public image can be saved from disgrace.
Stevie then enters, dragging a dead goat. With directions from Ross to the farm where Sylvia was kept, she found and killed the goat, because she could not stand the idea that she and Sylvia loved Martin equally, and were loved as equally by him. The scene and play ends with a tableaux as Ross freezes, Stevie remains emotionless, Martin breaks down in tears, and Billy quietly tries to address his parents.
