When a couple decide to spend their summer vacation in a small town on the coast of Portugal, they had no idea that they would be faced with a dark mystery that would lead to seduction and betrayal. Mar is an erotic thriller set in the beautiful coastal town of Peniche Portugal. It's main characters Xavier and Eduardo visit a childhood friend Cristóvão (Diogo Tavares) who carries a dark secret that only his mother knows. Sexual tensions rise until the shocking secret is revealed but only after someone's fate is sealed.
Lazarus de Jesus is the adopted son of a wealthy lady from Lisbon, whom he calls Grandmother. It is she who introduces him to Godfather, a great businessman who takes him as his protégé, and Angelina, the woman Grandma wants him to marry. But Lazarus has other hidden interests, the most important of which is an obsessive fixation on female armpits. When he sees the violinist Maria Pia playing, Lazarus immediately falls in love and starts to live for her, which will precipitate an absolutely unpredictable ending.
Lúcia is a lawyer that works to help women whose the father of the relationship deny the paternity. A job she is very keen about since she doesn't know who her father is.