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.

Once again Abby and her brother Jonah go through the magic mirror in their basement, and this time they find themselves interfering in the Little Mermaid story--and needing to set things right and make sure everyone has a happy ending.

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.

Lucas and Clara are floating on a raft when a wave casts them into the sea, where Lucas catches a glimpse of a coral kindom and a dark-haired mermaid helps him, but when his father, King Caleb, hears of this, he scolds Lucas and tells him he has broken an age-old pact.

"As princess of the island kingdom Visidia, Amora Montara has spent her entire life training to be High Animancer--the master of souls. The rest of the realm can choose their magic, but for Amora, it's never been a choice. To secure her place as heir to the throne, she must prove her mastery of the monarchy's dangerous soul magic. When her demonstration goes awry, Amora is forced to flee. She strikes a deal with Bastian, a mysterious pirate: he'll...

When she incurs Neptune's wrath by finding a diamond ring buried under rocks in the ocean, Emily is put under a curse that will force her to choose to be either a mermaid or a human and split up her parents forever.