Scholars have made many suggestions. Some authorities tend to argue for the historicity of the record, finding reasons to affirm that a fish could swallow a person live. Many others have read it as fiction, regarding it as didactic narrative, or a novella, a short story, or even a satire of Jewish piety. The main character in the book is Jonah. The book's date of composition, however, is uncertain.
Many scholars place it in the postexilic period.
This is the story line. Yahweh directed Jonah to go the Nineveh, the capital city of the Assyrian empire. Jonah went by boat in the opposite direction, so Yahweh sent a storm to stop him. The sailors determined that Jonah was the cause of the storm. After considerable moral anguish, they threw Jonah overboard and the seas calmed.