Summer on an island. When school starts after the summer break, Mattis and his friends will go to a high school on the continent. Meanwhile, Mattis works on a fishing boat. In the port and on the sea, he discovers a world he never knew before.

A couple of fisher-folk are joined by a young new apprentice in the middle of a raging storm.

Maryline, 16, is in love with Aymeric who works with her at the harbor. But under the influence of Mars on this summer day, she saves Ludovic from drowning.