Mathieu is a marine biologist. He spends his time on his microscope, cutting tiny marine organisms corpses. He's unhappy. His true wish would have been being on the sea. But an event will abruptly change his life: Christine, his mother in law, runs away. Attracted by this impulsion, and curious to understand her, Mathieu starts looking for her. He's going to find her in a house by the sea and will share the same desire of regaining control of his life.