In a large reception hall in the imperial palace the members of the court wait for the emperor to wake up, eavesdropping and spying through the keyhole in the door. A trumpet blast announces the arrival, from the stalls, of the emperor, who, having just got up, checks on the condition of his tongue in a mirror. What to wear? The ever more preposterous suggestions of the officials are drowned out by the arrival - announced by another trumpet blast - of two tailors. The older of the two sings the praises of a miraculous fabric, a fabric that is lighter than air and that cannot be perceived by anyone who is not worthy of it. Astonishment and terror assail the members of the court: His Majesty orders a suit made out of the material for himself. The Queen appears and she too in an aria brimming with wrath demands a garment for herself. In the final concerted number the entire court withdraws, leaving the tailors to their work.

Left alone, the two tailors sing to themselves a suspicious little tune about a “suit made of nothing”… The Chamberlain appears: he reveals a certain number of doubts about the suit but quickly converts these into expressions of confidence, especially after the arrival of the Court Official, to whom he hastens to point out the marvels that he claims to see. A flurry of activity offstage signals the arrival of the entire court: fed up with waiting, the sovereign couple are determined to inspect the new clothes. Immediately the tailors realise that the only thing they can do is pretend: to the music of a march the Emperor decorates the two heroes with two huge medals.

The clothes must be tried on! To the accompaniment of lavish compliments on the part of the courtesans the tailors first undress… and then dress the sovereigns. A sequence of trumpet blasts announces the beginning of a parade that fills the auditorium: the Emperor and Empress show themselves on the balcony, amidst the howls of the crowd – the tailors meanwhile stuffing their suitcases with gold and silver – amongst which the sole voice of a child unveils the truth: “Their Majesties aren’t wearing anything at all!” In the general pandemonium that follows the tailors scurry away, while the emperor summons the executioner. But to execute who? The two swindlers? A lone official calls on the public to protect and provide an escape route for the little boy that told the truth.