Ryn, Ben, Maddie must recruit new allies in the fight against Tia. Helen seeks answers when she's haunted by Donna's spirit. Tia obtains dangerous weapons she plans to use in her fight. Xander struggles to make amends with Annie.
Ever since Commander David Kyle's death in "Borders", the personnel at the naval research facility have been investigating. Commander Anderson is now in charge.
Helen starts seeing Donna's spirit after visiting the merfolk's Spirit World. With the help of Sarge's spirit, Helen knows that Donna's corpse is still being held at the naval research facility.
When a mermaid/merman's grave has been violated, the spirit of the deceased becomes one with another living human or mer-person, the corpse must be properly buried the in the water before the spirit can finally be at peace.
Another fact is learned about the Siren song is when harnessed, it can be used to kill humans on a larger scale.
Tia plans to acquire more in numbers from the north, find the males protecting Hope, and then execute the attack on Bristol Cove.
She uses explosives to sink three fishing ships. Later, she uses them to destroy the underwater cavern where Ben, Ryn, and Maddie traveled to in "Serenity" causing a massive cave-in. These explosives appear to have been made by the Russians given the white letters, this could foreshadow that Tia has a large arsenal at her disposal.
Xander maps the locations of Tia's path: the first and second ships were sunk off the coasts of Port Hardy and Ketchikan, the third one was sunk in Fredrick Sound in that order leading north to Nome, Alaska.
Ryn travels in an airplane for the first time.
Robb is a full-blooded merman, but despite that, he can no longer change into aquatic form. This is because he has been between land and ocean too many times, the transformation would take longer and would become extremely painful to endure. Eventually, he stopped transforming completely, forever remaining in human form.
Ryn sensed Ben's improved abilities, and Ben admits to her about his stem cell experimentation.
There is accumulation in the transition tide pool, the microplastics denies the mermaid tribe's ability to change sex. The polluted water contains BPA which emulates estrogen, too much estrogen in the water prevents the transition. Ben, Ryn, Robb, and Maddie do the following to solve the problem:
Water is polar while oil is non-polar, objects such as plastic bond to the oil. The reason they use vegetable oil is because it is non-toxic; therefore, it can separate the microplastics from the water after the oil is magnetized.
Magnetite is the most magnetic mineral on Earth, also harmless. When it is added to the vegetable oil, magnets can be used to remove the microplastics from the transition pool restoring it back to health.
Yura promises to aid Ryn in the war.
Robb is welcomed back to his tribe.
She needs you. You must help her or she will never leave you.
— Eliza to Helen about Donna's spirit.
Yura, I came to land to find a way of cleaning the oceans for good. To help our entire species, not just out tribe.
— Robb to Yura
You were chosen. Meant to provide us with children for generations. But you abandoned us. You left us to die. And that is what happened.
— Yura to Robb
I sense it in you. You felt Hope's heartbeat. You fought with the strength of my people. How can you do these things?
— Ryn asking Ben about his abilities
Hey I'm-- I'm sorry. As if being from the water wasn't enough. Now you have to cope with the fact that I was born female.
— Robb apologizing to Maddie
Ryn, however I feel about Robb, that will never change how special you are to me.
— Maddie to Ryn
It's not. What matters is who you are in here. That hasn't changed.
— Maddie to Robb
No. But I think about it a lot. I don't want to choose between land and water.
— Ryn talking to Ben about the inability to turn into mermaid form
Our swim was very special to me.
— Ryn speaking to Ben
Siren Season 3, Episode 7 Trailer A New Mermaid Tribe
Siren Season 3, Episode 7 Sneak Peek Helen Has A Vision Of Donna Freeform
Siren Season 3, Episode 7 Sneak Peek Ryn's First Flight Freeform
Siren Season 3, Episode 7 Sneak Peek Xander Is Questioned About Ben Freeform
Siren Season 3, Episode 7 Ben & Ryn Share An Intimate Moment Underwater Freeform
Siren Season 3, Episode 7 The New Mermaid Tribe Refuses To Fight Freeform
Siren Season 3, Episode 7 Helen Seeks Help From Sarge Freeform
Siren Behind The Scenes Intimate Underwater Moment Visual Effects Freeform
Siren From Storyboard to Scene Season 3, Episode 7 "Northern Exposure" Freeform