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 returns to town and tries to connect with her daughter. Meanwhile, Ryn attempts to adapt to life on land.

Ryn fights to maintain leadership of the pack when the other mermaids question her loyalties. Ben interferes in a mermaid ritual causing friction between himself and Ryn, meanwhile, Helen discovers more about her family lineage.