As they search for their missing father near their Cornwall home, Sapphy and her brother Conor learn about their family's connection to the domains of air and water.

Aluna and Hoku, Kampii from the City of Shifting Tides, and their friends, Equian Dash and winged Aviar Calli, are determined to stop a war. The maniacal ex-scientist Karl Strand is planning to conquer the world with his enormous army of tech-enhanced soldiers-- unless the four friends can get to Strand first. Aluna's plan is dangerous: pose as Upgraders and infiltrate the army. But the enemy isn't what they expected and the strategy begins to crumble....

Twelve-year-old Macy is an amateur treasure hunter. She finds all sorts of lost things along the shores of Buffalo Pound Lake. When her mom announces she's leaving her quiet park ranger job at the lake to be a police officer in the city. Macy decides she needs to find a treasure big enough to put Buffalo Pound on the map so her family can stay put. But instead of treasure, Macy finds a mermaid! She learns that the frightened creature was kidnapped...

"One hundred years ago. On the foggy Hudson River, a riverboat captain rescues an injured mermaid from the waters of the busiest port in the United States. A wildly popular--and notoriously reclusive--author makes a public debut. A French nobleman seeks a remedy for a curse. As three lives twine together and race to an unexpected collision, the mystery of the Mermaid of the Hudson deepens" -- from publisher's web site.

When Lu comes ashore and adds her mermaid singing to a middle-school rock band, a threatening ancient prophecy follows her, so Kai and her other bandmates step up to come to Lu's--and the village's--rescue.

In 1684 France, Louis XIV, the Sun King, is the most powerful and influential monarch on the planet. But his birthday is approaching along with a rare solar eclipse and he's worried about the future of France. His spiritual advisor, Pr̈e La Chaise, comforts him, while his physician, Dr. Labarthe informs him that scientists believe mermaids contain a life force that grants immortality. Louis XIV's quest for immortality leads him to capture a mermaid's...

Little Scallop, a princess of the Mollusk tribe, longs to have a real adventure. So late one night, she and her mermaid friends sneak off to dive for pearls. They run into a fierce storm and a strange ship sailed by men who would love to capture a mermaid.

Two years after the disappearance of their father, Sapphire and Conor, having moved with their mother to the town of St. Pirans, try to make a new life for themselves, but Sapphire, unlike her mother and brother, finds it increasingly difficult to adjust to her new circumstances and is drawn more and more to the undersea world of Ingo.

Ruler by day, a reluctant pirate by night, 18-year-old Princess Ariana fights for her subjects in the waterfall city of Lunadar. In a kingdom surrounded by fairies and mermaids, and ravaged by deadly Drundles, only a chosen few are trusted to guard her daughter, Candra, as the secret heir to the throne. But it only takes one ill-fated meeting for Ariana to suddenly be plunged into an escalating web of secrets found in her father's journal, a deadly...

Nearly-ten-year-old Poppy Malone finds her skepticism challenged again when she must deal with troublemakers at Lake Travis who look and act suspiciously like mermaids, which she knows do not exist.