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

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…