After injury and setbacks, former swimmer An-na returns to her hometown. Sharing a home with the unfamiliar Deok-hyun and reconnecting with an old friend, she finds her once-stalled life quietly beginning to move again.

An-na sets out to learn diving from Deok-hyun, a Diver. As she confronts the sea's unforgiving nature, she's pushed beyond her limits. Amid the struggle, a subtle new rhythm begins to form between them, growing with each challenge they face together.

Their harvesting class begins during a slack tide. An Na moves forward one clumsy step at a time, and a new tension quietly stirs between her and Duk Hyun, whose indifference hides a quiet kindness.

The afterglow of An Na's first dive lingers over Parang-ri. But as their hearts draw closer, suspicions and old rumours surrounding Duk Hyun begin to form a crack in their calm lives.

An Na uncovers a secret that was never meant to surface, while Duk Hyun is forced to face a past he can no longer outrun. Together, they are pushed to the edge and tested on whether they have the courage to move on.

Despite an approaching typhoon and a canceled competition, An Na, Duk Hyun, Su Jeong, and Gi Tae refuse to give up. The four must each find their own way to keep moving forward on the unpredictable sea.