Donna declares war on everything and everyone on land or sea. Heading an attack on both the government and local fisherman boats. Ben is completely unaware of what is awaiting him in the waters. The environmentalist hero joined the maiden voyage to intercept the government ships that are harvesting Sirens. What Ben and the Bristol Fisherman crew find is a bloody and deserted ship. The uneasy feeling of vacant cages and spears sprawled over the ship floor is enough for to Ben to conclude that they need to abort the mission and head back to the docks.

However, the fisherman’s ship comes under attack by Donna and a male Siren counterpart.  Ben and Xander do their best to fight off the attack but lose a member of their crew, Captain Sean McClure (Xander’s father). Ben and Xander still grieving the loss of former Captian Sean McClure make the difficult decision to bury Captain Sean McClure at sea knowing that there will be no justice for his death due to the town’s unbelief in supernatural creatures, let alone Sirens.

Meanwhile back on land Ryn is booked into custody and held for questioning over the murder of Donnie (the man who attempted to rape Ryn). The innocent Siren answers Sheriff Bishop’s question with full honesty, however, she misunderstands the question of who helped her kill Donnie. To which Ryn simply names Maddie and Ben. The stunned Sherrif is in unbelief that his daughter (Maddie) may have a hand in murdering Donnie.

Maddie is summoned by her father’s Deputy back to the station. Sherrif Bishop reminds Maddie about her mother’s death by overdosing on drugs. Her father quick to assume that Ryn is on drugs by her strange behavior and somehow Maddie is involved. Maddie knows that there is only one way out of clearing Ryn’s name, telling her father the truth. Of course, Sherrif Bishop is not amused by what he believes are stories or lies. But when Maddie and Ryn are reunited, the Siren warns Maddie that Ben is in danger as her sister (Donna) has declared war on the waters.

Unable to save Ben, Ryn tries to free herself from her cuffs. Maddie calms the Siren down and coaxes Ryn into showing her father (Sherrif Bishop) what she is. After being made a believer, Sherrif Bishop releases Ryn from custody and may prove to be an alli to Ryn, Maddie, and Ben in the future. As more death and mystery washes up on the shore of Bristol Cove.