Kathleen Bell 
Another Dimension – Journey Into the Unknown/ Friend or Foe [EPUB ebook] 

Katy discovers a strange object whilst digging in the garden, which allows her to travel through portals, to other worlds and dimensions, and even though time.On her travels, she meets a boy called Lee, who quickly gains her trust, (and her heart, ) and helps her out of some sticky situations.However, keeping their secret from friends and family, and the most popular girl in school, Judy, (whose sole ambition seems to be making Katy »s life miserable, might not be so easy.Lee also has some other gadgets, which come in very useful, when the device falls into the wrong hands and friends and family start disappearing.