The military spy on Ben, Maddie, and Ryn, while the mermaid struggles once mating season begins.
Ryn takes Ben and Maddie to a secret place below the ocean. Levi returns to land.
Ryn returns to Ben and Maddie. The thrupple must learn to trust an outsider.
Ben struggles with the siren's song effects, but Ryn also struggles with her feelings for him and Maddie, too.
Ben struggles with the siren's song. Xander finds out about the merpeople on land.
Helen reveals more of her history. Bristol Cove deals with the aftermath of a merfolk attack.
The merfolk have a civil war between their hierarchy on land, involving everybody in Bristol Cove.