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.
Bristol Cove mourns, as Xander discovers the truth about Ryn.
Ben goes out to sea, trying to thwart the military. But there's worse trouble than the government on the water.
Ben works with his Ted, to find info from the inside. Maddie gets to know Elaine better. Chris returns to Bristol Cove.
The longer Ryn is out of the water, the more she deteriorates. At the military compound, the other mermaid causes chaos.
Ben tries to help Ryn, but the mermaid is only concerned with finding her sister again.
Bristol Cove - a town already obsessed with mermaids - is thrown into disarray after a mysterious young woman turns up.