Ryn’s sister makes a break from the laboratory and seeks the help from Chris (the fisherman hurt by the Siren before capture). The laboratory comes under fire for the breach of security and the escape. Leading Aldon Decker to discover that the Siren was observing them while in captivity and planning her escape from day one. The government decides to conceal all loose ends and burn down the facility in hopes to keep what happened at the laboratory a secret.

Ryn tells Helen that the reason her sister was captured was by the fascination she had to come to the ocean’s surface. Ben and Maddie go to break out the Ryn’s sister from the laboratory but are called back by Helen. Ryn’s health is on the line after being out of the ocean water for too long. Ryn in protest wishes to not return to the ocean until her sister is found.

Ryn finally gives in to be returned to the ocean after some convincing by Maddie. Allowing Ryn choice to wear a tracking bracelet in order to keep the Siren safe in the water and knowing when she returns to land. However, just before Ryn returns to the water Ben receives a text that Chris is alive. Leading the Siren to believe that her sister is with Chris and alive.

Ryn is reunited with her sister and together they return to the ocean. While Maddie and Ben watch from the shoreline as the Sirens swim back to freedom. However, the Sirens may still be threatened with Aldon Decker on their trail. Here’s hoping that Ryn’s tracking device works in time for Ben and Maddie to protect them!