It's Christmas Eve in Naples. Little Rocco feels increasingly jealous due to the imminent birth of a baby brother. Three bungling devils sent by Satan promise him that if he'll stop Jesus from being born—entering the Nativity scene his father built by the magic word "opopomoz" and altering the past—his brother won't be born either.
Momo is a shy and affectionate girl who has found new friends and a house in the middle of some ruins of an old amphitheater. But suddenly, a day, the "Grey Men" burst in the city in order to rob people's time. Momo try to stop them but doesn't know how.
A seagull is caught by the black tide of a sinking petrol ship. She manages to fly inland and falls down in a garden by a cat. Moribund, she asks the cat to fulfill three promises: that when she lays her egg he must not eat it; that he must take care of it until it hatches; that he would teach the newborn how to fly.
