A diver from the Venice Arsenal accidentally dies during a dive ordered by the admiral.
Anna, the diver's only daughter, accepts the hospitality of an old friend of the family, Antonio, whose worker son immediately falls in love with her.
During her funeral, however, Anna meets Luciano, a young officer and son of the admiral; a sympathy arises between the two, but one evening Anna sees the officer at the port exchanging affections with a stranger before leaving for a mission at sea.
Meanwhile, Antonio, seeing his son first deluded and then humiliated by Anna's turnaround, asks the admiral for an audience and protests with him revealing what had happened.
The admiral summons the girl and, after having severely reprimanded her, informs her of the decision to prevent her wedding with Luciano.