Chief mining engineer Katla embarks on a governmental mission to survey a territory of deep-sea minerals in the North Atlantic. On the research ship Explorer, Katla and her engineering team, a group of scientists and the ship’s crew sail towards the survey area in harsh weather.
The closed off and gruff captain of the ship, Sigriður, challenges the decisions of ambitious and ardent Katla who leads a sea mission for the first time and treats her new environment on board like an exciting playground. Katla engages in a silent battle of will with the equally headstrong Sigriður who she feels both attracted and repelled by. The mysterious captain resists her – Sigriður’s only Master is the sea.
The Explorer reaches the survey area. All-consuming Katla digs deep into the ocean soil and the humans around
her. She pushes her team to work hard day and night, but the sea doesn’t act in Katla’s favour. She is overcome by maddening seasickness and the mission’s progress doesn’t meet her ambitions. When a deadly accident happens, Sigriður warns Katla of defying the sea – it is unpredictable. The weather deteriorates and demands Sigriður to navigate the Explorer back to land, but Katla wants to continue her mission. In the end, the sea decides her fate.