The Last Portal — Robert Cole

Severe weather patterns - storms, floods and strong winds - are sweeping across planet Earth. Against this backdrop, three high school students, known and tormented for their strange abilities, fight their own battles against school bullies. The discovery of a strange key by their leader Chris Reynolds, plunges all three through a portal into a sister world, Cathora, in another dimension. In this world, their behaviours that labelled them as misfits on Earth, turn out to be the seeds of extraordinary powers. They soon meet Batarr, the Guardian of the portal. He tells them they are not normal children, but are part of a group of six beings, called Mytar, who are periodically seeded throughout the dimensions to fight planetary invasions across these portals. Cathora has been invaded by an alien army, led by a creature known only as Zelnoff. After conquering Cathora, his next target is Earth. The Mytar alone have the power to stop him if the other Mytar on Earth can be found. There ensues many struggles and battles as Chris, Susie and Joe seek to evade Zelnoff's forces long enough for their powers to develop so they can detect the remaining Mytar back on Earth.