Living with his grandfather on an island off British Columbia, orphaned ten-year-old Daniel feels deep loneliness until the night he meets a mermaid whose identity he tries to learn.

When Neptune tells Emily and her merman father and human mother to return to Brightport to try to make merpeople and humans work more closely together, Emily faces problems with old enemies, her new, half-merfolk friend Aaron, and a mystery related to a group of legendary lost sirens.

Racing to bring the magic crystals to the Coral Kingdom, the six young mermaids discover a dolphin trapped in a fisherman's net, thanks to the evil Mantora, and Sophie, the fastest swimmer, rushes off to find help.

Visiting her grandmother in the Louisiana bayou, ten-year-old Maddy begins to realize that she may be the only sibling to carry on the gift of her family's magical legacy.

Transformed by the goddess Yemoja into a Mami Wati, an African mermaid charged with collecting the souls of those who die at sea, Simi goes against the gods to save a living boy, Kola, from drowning.

While vacationing in the Bahamas, Jade, who is part mermaid, uncovers a mystery.

"Set in the ocean off Japan, this retelling of Goldilocks and the Three Bears stars Kiniro, a mermaid, who finds a baby octopus's breakfast, chair, and bed just right"--

"Astrid struggles with a shameful secret, Ling discovers courage in a prison camp, and Serafina lines up allies to help fight the final battle for her underwater realm"--

"The Princess in Black and her friends are enjoying a day of sun and sea on Princess Sneezewort's royal boat when a real, live mermaid princess emerges from the waves! Eeeeeee! Princess Posy needs their help protecting her very cute sea goats from being eaten by a very greedy kraken. But the princesses and the Goat Avenger quickly realize that fighting underwater can be tough for land dwellers, and only the mermaid Princess Posy can save the day....

Holly must solve the puzzle of an old legend if she and the other mermaids are to stop the toxic waste leaking from a wrecked ship, threatening a family of turtles living nearby, and get back to their vital mission for Queen Neptuna.