The submarine Enrico Toti returns to its base at the end of a mission. After a brief leave, the crew members, who have embraced their families, return to sea. They encounter a British submarine, HMS Triad, ram it, and sink it. The main character in the film was actually a submarine commander: Lieutenant Commander Bruno Zelich, who would die shortly after filming while commanding the submarine Sciré.
| Actor | Role |
|---|---|
 Giuseppe AddobbatiNot listed | Not listed |