The Metropolitan Opera is looking for the sea monster reported in newspaper headlines, because this monster sings beautifully! The "monster" is actually Willie, a whale who can sing in several voices simultaneously. A friend of his, a gull called Whitey, tells him about the searching ship, and Willie goes to audition, as it's been his ambition to perform on stage. Unfortunately, Professor Tetti Tatti from the Opera believes that one or more singers have been swallowed by the whale, and need to be rescued.
- As the story opens, strange operatic vocals are soon heard far out at sea. Some sailors soon report something that leaves many flabbergasted: the vocals are emitting from a whale!
The public and a number of notable people are split: some refuse to believe, while others accept the miraculous story.
The story soon reaches the desk of opera Impresario, Professor Tetti-Tatti. After thinking long and hard, the Professor can only come to one logical conclusion: the whale has swallowed an opera singer!
The Professor charters a crew and publicizes his quest. A lone seagull named Whitey just happens to see a newspaper article telling of Tetti-Tatti's search, and takes it out to sea to show his friend: Willie. Willie hasn't actually swallowed an opera singer, but can really sing. When the seagull shows Willie the newspaper, Willie assumes that the Professor is looking to audition him, and given Tetti-Tatti's credentials, Willie feels his dream of singing at the Metropolitan Opera may finally come true!
Willie soon comes upon the Professor's boat, and begins to sing music from "The Marriage of Figaro." Tetti-Tatti demands that his crew harpoon the whale (thinking by killing it, he'll save the opera singer inside, as he believes), but the crew soon grows enamored by Willie's vocals, and applaud for more.
Willie soon proves to be a 'singing miracle,' when he begins singing in 3-part harmony, able to sing in Tenor, Baritone, and Bass. The crew is impressed, but Tetti-Tatti now believes that this whale has swallowed 3 opera singers!
Willie continues to sing, as the audience is drawn into his imagination, as he imagines himself on the stage of the Metropolitan Opera, singing numerous other arias.
However, Tetti-Tatti soon breaks free from the crew, and harpoons Willie, killing him.
In the closing narration, we see Whitey the seagull who was Willie's friend, dejected over the loss. But the narrator explains that the audience should not feel anger towards Tetti-Tatti, and that some people just aren't used to miracles.
The narrator closes by explaining that somewhere in heaven above, Willie still sings, but in 1,000 voices. The closing image shows Willie in angelic garb, singing in a choral tone, before we see the gates of heaven showing that the performance is sold out to see Willie perform.