"Once a Greech" is set on the planet Kish, where the Greeches, a race of highly intelligent and technologically advanced beings, reside. The Greeches have a strict caste system that determines each individual's role and occupation in society. The protagonist of the story is a young Greech named Zog, who is dissatisfied with his assigned role as a technician and dreams of becoming an artist.Despite his lack of formal training, Zog possesses a natural talent for painting and sculpture. He spends his free time creating works of art in secret, hiding them from his family and peers who would disapprove of his unconventional pursuits.When Zog's artistic talents are discovered by a visiting human ambassador, he is offered the opportunity to study art on Earth, where his skills would be appreciated and celebrated. However, Zog must overcome the strict societal norms and expectations that govern Greech society if he wants to pursue his passion.As Zog grapples with the decision to leave his home planet and pursue his dreams, he must confront the prejudices and obstacles that stand in his way. He faces opposition from his family and peers, who view his artistic aspirations as frivolous and impractical.