From the World of Percy Jackson: The Wild Zone

When Katie Kim arrives at Camp Half-Blood, she knows nothing about Percy, Luke or the demigods who are rooting for Chronos. Same as four other new demigods - and possible new friends - she slowly discovers the camps´ secrets, while visiting the mysterious and very dangerous Wild Zone several times. The story takes place between Lightning Thief and Sea of Monsters, which means that some of our favorite characters aren´t in camp or even known yet. Luckily, Katie, Zuri and the others are just as cool and fun to read as Percy and his friends. "The Wild Zone" is a must-read for every Riordan Fan. It´s so cool he´s working with those talented authors for his ´side-novels´ and I really liked going back to Camp Half-Blood, learning more about some areas we´ve never seen before.