Gregor, a travelling salesman, awakens one morning only to discover that he has transformed into a giant insect. His family is repulsed by him not knowing what to do. Gradually things start getting overturned because of the mishap, and Gregor's life crashes like a house of cards.
The Metamorphosis was first published in 1915. It's Author Franz Kafka is well known for his exploration of the fantastic and isolation. He uses realism to depict bizarre situations. In The Metamorphosis, he incorporates themes like alienation and absurdity to convey narratives about isolated and anxious protagonists.
The story does not mention the time period, but it's probably early 20th century. The whole narrative takes place in Gregor's apartment with his family and sister.