One morning, as she gazes at the starry sky giving way to dawn, a spaceship from outer space crash-lands next to her. On board is Stella, a daring shooting star who urgently needs to find fuel to be able to return to space!
Together, they embark on an exciting quest under the oceans. During their journey, Astéria introduces Stella to the fascinating diversity of marine species, while Stella shares her knowledge about Earth, the Moon, and the Sun. Exploring the deep oceans of Earth and exploring deep space have many similarities, which the two friends discover during their adventure. Gradually, they realize the magical connection that ties underwater life to the vastness of space.