Cecilie, Ewan, Amelie, and Nachton, 4 teen siblings get lost at the Atlanta airport and end up in Overtwixt, a world of floating islands also known as nilands. The villain Vizier, also a human from their world, broke the bridges. To go home, they have to defeat Vizier and rebuild the bridges.
It's a very strange place where time passes differently at different places. People have animal-like bodies in the shape of horse or bats or dragons but they can still talk and think like humans. There are no animals here. This place has 5 fundamental laws. There's no blood, only yellow puff replacing the blood. One cannot be killed in Overtwixt.
In Overtwixt, these siblings choose to be a Knight, Princess, Empress, and Loremaster. Ewan, who chooses to be the Knight learns riding and sword fighting. Empress Amelie has to unite the people from other islands against Vizier. Loremaster Nachton spends months in the library, gains knowledge of this place, learns magic and the fundamental laws of Overtwixt. He gets to know that there are some ancient magical relics like Diamond sword, armour and eyeglass lens which can multiply one's power only if they are used for the greater good. With efforts, they acquire the armour and lens but the sword still lies with Vizier however the sword cannot multiply Vizier's power since he is evil.
Vizier is still unaware of these 4 siblings. The siblings along with their allies plan a surprise attack on Vizier.
It's a really exciting story from page 1. You'll want these kids to quickly find a way to get back home but their adventurous journey is filled with unexpected twists and dangers.