Longing for onstage stardom, Pearl auditions for the third-grade play and gets the part of the evil sea witch while her best friend is cast in the lead, a situation that challenges their friendship.

Wanting to help a lost baby polar bear return home, Kiki Coral and her mermaid friends worry that the cost of the bear's transportation will prevent them from seeing a concert performance of their favorite boy band.

Mermaids Shelly and Echo are excited to begin third grade at the prestigious Trident Academy, but snooty Pearl, jokester Rocky, brilliant Kiki, grumpy Mr. Fangtooth, and an argument over their first project challenge the best friends. Includes facts about marine plants and animals and words to the Mermaid Tales Song.

While Kiki and Echo help Shelly prepare for a royal tea with her visiting great-aunt, Queen Edwina, Shelly worries that the Queen will make her leave Trident City and move to Neptune Castle.

A shark has been spotted in Trident City! Pearl Swamp is so scared, she needs a shark Guard to escort her to and from school. She doesn't trust anyone who likes these terrifying creatures, especially Kiki Coral, who isn't nearly as frightened as Pearl. And to make matters worse, Pearl accuses Kiki of stealing her precious pearl necklace! Will the sharks destroy the peace of their sparking city? Or will the mergirls have to swim in dangerous deep-sea...