Momo arrives in the city and meets Cassiopeia and Beppo. Beppo wants to prevent, that Momo is taken to an orphanage and tells her about other children and the amphitheater.
Momo has her new home in the amphitheater- to the dislike of Gigi. While she helps the inhabitants to settle their quarrels by only listening to them, Grey Men are scurrying through the city.
Momo goes with her friends to school and the have a lot of fun during the lessons. But suddenly two Grey Men appear to persuade the teacher to save time.
Nino, who has been visited by a Grey Men, expels his Uncle Ettore and the other old men out of his restaurant. Momo has to find a way to bring them back together.
The Grey Men, who are aware, that Momo is a great threat, assign the Agent100 for the case. He tries to persuade Momo with a doll called "Bibigirl", but Momo's will is stronger.
Momo wants to tell the children everything she knows about the Grey Men. But the Grey Men try to prevent that by setting up a fairground and luring the children away from Momo
Together with the children Momo is preparing a children's demonstration to warn the inhabitants about the Grey Men. Unfortunately the grown ups don ́t pay any attention to them.
Momo is persuaded by Cassiopeia to leave the amphitheater just in time, before the Grey Men arrive there. Beppo, who witnessed the big tribunal of the Grey Men, thinks that they have kidnapped Momo.
The Grey Men are chasing Momo, but she manages to escape thanks to Cassiopeia's gift to look into the future. Meanwhile Beppo asks Gigi to help him find Momo.
Momo meets Master Hora and learns everything about the secret and the origin of time. Gigi delays his search for Momo to go to a TV-casting and Beppo is taken away to a mental institution.
Momo awakens in the amphitheater and sees, that the city has changed completely. It doesn't take long For the Gery Men to realize, that Momo is back, while she finds out, that she has slept for a whole year.
Momo goes to Gigi's house, who meanwhile became a big TV-star. Even he is so busy, that Momo has to admit to herself, that she also lost Gigi to the Grey Men. Agent 1313, who is accompanying Momo, has no good intentions in mind.
Momo is at the TV-station, because she wants to ask Gigi to help her find Beppo. In front of the cameras she appeals to the viewers. The Grey Men start chasing Momo, but they can only capture Cassiopeia.
Momo goes with her friends home to spend some time with them. She succeeds in bringing back the cheerful mood. But the Grey Men are watching them and are ready to make their next step.
Momo is waiting for her friends. She decides to go to the children's depot. But she is discovered and has to escape again. The president himself approaches her to make her a proposal.
After Momo has not accepted the president ́s proposal, she is locked away in a cell. She manages to escape, but has no idea, that this was the intention of the Grey Men. They want Momo to lead them directly to Master Hora.
Momo arrives at Master Hora ́s house. The Grey Men instead cannot follow her through the never-lane, because the would start to disappear. Master Hora needs Momo's help to beat the Grey Men. She bravely agrees.
Master Hora shows Momo the hour flowers to explain her, where her own time comes from. While she is still enchanted by the sight of the hour flowers, she falls asleep.
Momo sneaks into the hiding-place of the Grey Men. The Grey Men disappear one by one and Momo manages to free the frozen hour flowers. Time and Life starts to blossom again.
