Thirty-year-old Alice is a sailor about to embark on a journey she will not soon forget. Leaving her fiancé Félix ashore, she joins the crew of an old cargo ship, the Fidelio, as a mechanic. Once on board, Alice discovers that she is replacing a man who has just died and that Gaël, the first great love of her life, is the ship’s captain. Lulled by life aboard the ship and entranced by the limitless horizon of the wide open ocean, Alice succumbs to desire and begins an affair with Gaël. But she soon faces a difficult choice about what will make her truly happy: an unfettered life at sea, or grounded happiness at home?