The Irving Siblings: Return to Mako Island

The Irving Siblings: Return to Mako Island (internationally released as The Irving Siblings: An H2O Adventure) is an American-Australian television programme targeted towards kids and teenagers. Like Mako Mermaids, the series is a spin-off of H2O: Just Add Water, produced by Jonathan M. Shiff in association with Network Ten and Nickelodeon America.

The series follows the Irving siblings, a group of half-human half-mermaids originating from the Northern Pod who travel to Australia in hopes of protecting Mako Island from a potentially dangerous string of Full Moons.

Plot
A young mermaid named Nina falls in love with a land boy named Jonah Irving. Although a romantic relationship between a land dweller and merperson is forbidden by the Northern Pod, the two lovers decide to break the rules. Using her Moon Ring, Nina gains legs and moves in with Jonah in his hometown of Florida. The two eventually get married and have five children together.

With Nina now being outcast from her own pod, a few merpeople decide to take revenge and murder Jonah so they can bring Nina back in. Unfortunately, their plot doesn’t go as planned and Nina is killed in the process. Along with that, Jonah gets fired from his job at the marine life institute due to an accident that happened in the ordeal. While studying on mermaids, Jonah discovers of a certain string of Full Moons that would happen fifteen years from now, resulting in major havoc for any pod that it crosses, each moon stronger than the last. Now with a resentment for mermaids and a vow to avenge his wife, Jonah moves to Australia, becomes a self-proclaimed scientist and uses his marine biology knowledge to try and strengthen the Full Moons to kill off the entire mermaid population once and for all.

What about his five children? After Jonah moves to Australia, they’re taken in by his sister, Janine Evens. The siblings live a double life, both as human kids residing in Florida and merpeople of the Northern Pod. When Vivien, the oldest, is informed of where his father is and what he’s doing, the siblings decide to leave the United States and move to the Gold Coast, in hopes of protecting all merpeople alike and stopping their father’s malicious schemes.

Zac from Mako Mermaids makes a guest appearance during the season 3 finale.

Protagonists

 * Ashley Johnson as Vivien Irving, the oldest of the siblings at 19. Vivien acts most like a mother to the other four, always being the one to keep them at bay and get them out of trouble. She’s the only one out of the siblings who has a Moon Ring, originally inherited from their mother and given to her due to her status as the eldest. Due to never going to mermaid school, she‘s mastering how to use it on her own.
 * TBA as Eirene Irving, the second oldest at 16, and the most inclined to the sea and mermaid culture.
 * TBA as Hurley Irving.
 * TBA as Dax Irving.
 * TBA as Myuna Irving.