Alain Decaux raconte (1969)

Momo, a little orphan girl, lives in the ruins of an old amphitheater in a small town. Her extraordinary ability to listen draws people to her and she has many wonderful friends. One day she becomes aware that something has changed. Looking further into this, she comes across the "Grey Lords", a powerful secret organization that is aggressively influencing people to save time and give it to them. The Grey Lords can only continue to exist with the time saved by others. Only Momo recognizes the danger, and she is soon practically the only one who can do anything about it: none of her friends have any time left! With the help of the tortoise Cassiopeia and Master Hora, the Lord of Time, she begins a long and adventurous battle against the Grey Lords to save her friends and give them back to all the time in the world!