When Countess Pearl visits King Triton and his daughters, she finds out about Princess Ariel's collection of human objects and uses the information to make Ariel do whatever she orders

Mermaid Queen Nefazia of the Indian Ocean shows up at Triton's palace, and the princesses are enchanted, until they begin to believe that she's come to marry their father. Aquata convinves her sisters that having a stepmother around would ruin their lives, so she comes up with a plan that will drive Nefazia away forever. But Ariel thinks Nefazia would make a terrific stepmother. Can she stop Aquata's awful plan before it's too late?

Everyone at the palace thinks Adella's new best friend, Arsulu, is wonderful. But Ariel has her doubts. Why is it, she wonders, that ever since Arsulu came to stay with them at the palace, strange and terrible things have been happening? A suspicious Ariel decides to spy on Arsulu to see if she's really to blame. That's when she learns the horrible truth about Arsulu. But how can Ariel convince her sisters that their dear, sweet guest is really a danger to them all?

Ariel and her sisters are bored at the thought of singing in the Under the Sea Musical Gala. They suggest performing a play instead, but Sebastian, the royal court composer, says absolutely not.

The mermaid princesses can't wait to arrive at the new summer palace - all except for Arista, that is. This is to be a summer of dinners, dances, and lots of aristocratic boys! But boys or no boys, summer without her favorite sea horses to ride is not Arista's idea of fun until she discovers the brand-new stables at the summer palace - and the stablehand, Dylan. Suddenly summer takes an exciting turn for the better! Spending time with Dylan is great, but Arista worries how King Triton will react to her new boyfriend. Will she have to keep Dylan a secret from her father forever?

When Ariel reads a thrilling biography of the famous mermaid spy Mata Herring, she starts to do some snooping around herself. Suspecting that her substitute teacher, Mr. Kipper, is up to no good, she convinces her best friend, Coral, that Mr. Kipper has kidnapped their real teacher, Mr. Chubb! Unfortunately, nobody believes Ariel's outrageous accusations, and King Triton demands that she stop her spying routine. But in the tradition of the great Mata Herring, Ariel knows she must continue her quest and help save her teacher - even if it means going against her father's wishes!

When the Circus of the Sea arrives in King Triton's kingdom, Ariel and her sisters can't wait to explore the big top, visit the sideshow attractions, and meet the weird and wonderful circus folk. One of the weirdest is Merseer the fortune-teller, who warns the princesses that their father's life may soon be in danger. At first they're skeptical, but when some of Merseer's other predictions start coming true, they begin to wonder. Could the terrible prediction about King Triton be right as well? And if it is, will they be able to change the future and save their father's life?

King Triton and his daughters have traveled to the icy waters of the Artic Ocean to visit an old family friend. Soon after they arrive, the princesses learn that the palace where they're staying is rumored to be haunted by the ghost of a merman named Morven, who died a horrible death there many years earlier. At first Ariel and her sisters are skeptical, but when strange and spooky things begin to happen, they have to admit that it really does seem as if someone - or something - is after them. Could it really be the ghost of Morven?

Ariel's sister Attina has always been more interested in books than in boys, but lately her sisters have noticed that she's been spending even more time in the library. They soon discover why - Attina has a crush on one of the boys who works there. She's too shy to ask him to the upcoming school dance herself, but when flirtatious Adella tries to help, she accidentally fixes Attina up with the wrong boy! Can the mermaids come up with a plan to give Attina's love story a happy ending?

Life under the sea is never dull for the mermaid princess Ariel and her six older sisters. Their adventures continue in these two short and lively novels. Full color.