In the season finale, the enchanting siren song takes hold of Ben and Decker. Meanwhile, Dale must answer for the escalating crime in Bristol Cove.

The coastal town of Bristol Cove, once known for being home to mermaids, is turned upside down with the arrival of a mysterious girl.

In an effort to save Hope, Ryn and Ben confront Tia in an undersea battle between the mermaid tribes. Maddie and Robb work to find a cure for Xander, while…

As an old friend visits Helen, a new mermaid arrives leaving Ryn questioning their motives. Maddie learns the truth behind Ian’s death, as Ben fights for his mother’s treatments. While…

Ryn goes back to the ocean to get help for Ben and Maddie’s conditions but discovers that continuing to go back may get harder than she realized the longer she’s…

Mermaid mating season has begun, with Ryn knowing she will need to go back to the sea to help her colony. The hybrids convince one of the mermaids to come…

Mating season turned out to be less successful than everyone had hoped, leading them to question the possibility of the mermaids procreating on land. Ryn brings a new mate ashore…

Ben and Xander are left dealing with a shocking discovery about Chris and his connection to the military. Meanwhile, Helen and Maddie reluctantly seek help from the hybrids as the…

Ben faces a choice that has rippling consequences amongst mermaid, hybrid and human alike, as the truth about mermaids is exposed.

With Elaine Pownall’s health worsening, she seeks treatment from the military’s medical trial using mermaid cells, but the procedure doesn’t come without side effects to the mermaids. Meanwhile, Helen and…

Maddie and Ben contend with how to help Ryn knowing that in order to help Elaine get better, they will need to continue the procedures on Ryn. Meanwhile, when one…

With more mermaids landing at Bristol Cove’s shores, the threat of discovery increases. After his encounter with the siren song, Ben tries to cope with the after effects. Maddie’s mom…

When Ryn is taken in for questioning, Maddie rushes to her rescue. Meanwhile, Ben and Xander return to the deep sea to search for answers, only to be met by…

Bristol Cove mourns a loss causing Ryn to experience a new human emotion.

Donna comes ashore with two other members of her colony to bring Ryn back home. When mermaids once again begin wreaking havoc throughout the town, Dale tries to put an…

Dale and the local police’s investigation starts pointing directly to Ryn, meanwhile Xander and Calvin’s search for Chris heats up when they locate the nurse who works at the military…

When the military facility goes on high alert, Chris manages to escape, but he’s not the only one who gets out.

Ben begins to investigate some suspicious overfishing, meanwhile Decker ramps up his efforts to find his escaped mermaid and shows the true extent of his influence.

When Ben and Maddie attend his mother’s fundraising gala, an unexpected guest shows up and offers to put an end to the overfishing that’s threatening the lives of the mermaids…

Ben and crew of The North Star uncover a device emitting a strange sound. Meanwhile, Ryn finds shelter in the home of the local folklore expert.

When devastating truths behind the Mars attack are revealed, Picard realizes just how far many will go to preserve secrets stretching back generations, all while the La Sirena crew grapples…

Picard and Soji transport to the planet Nepenthe, home to some old and trusted friends. As the rest of the La Sirena crew attempt to join them, Picard helps Soji…

In the cult’s chambers high up in the Siren Tower, the surviving Blood Angels count the cost of their war with the cult. They are soon joined by Magos Dominus…

While Ancaeus’ surviving warriors follow Castia’s Servitors through the under-tunnels of Niades, the Tech-priest explains her plan to the paralysed Captain Orpheo. High above them, in the inner sanctum of…

Larry runs into a familiar face, causes a rift between expectant parents and seeks a second opinion on his knee injury. His reaction to emergency sirens spells disaster.

Six food truck teams meet up with Tyler Florence in Tampa, Fla., and are shocked to see a squadron of police officers arrive with sirens blaring. The officers are there…

The La Sirena crew begins an unpredictable and lively expedition on Freecloud to search for Bruce Maddox. When they learn that Maddox has found himself in a precarious situation, a…

After being accused of murder and having her criminal past exposed, Laurel goes full Black Siren and teams up with an old criminal acquaintance, Shadow Thief, to go on a…

Oliver, Diggle and Felicity disagree with Dinah, Curtis and Rene on how to handle Black Siren. The two teams face off and a fight ensues.

Oliver and Thea are shocked to hear that Roy Harper is back in Star City. However, when they discover the circumstances of Roy’s return, Oliver and Thea realize that Roy…

Despite losing half his team, Oliver remains confident that he, Felicity and Diggle can stop Cayden James and Black Siren. However, when he discovers one of Cayden’s secrets, he decides…