The Fire Chronicle by John Stephens

Three children. Two worlds. One prophecy.
 
Kate the eldest, keeper of the Book of Time was last seen fighting off a Screecher to save her siblings.
 
Michael is in charge now that Kate's gone. He needs to go to the ends of the earth to unlock the secrets of the Fire Chronicle.
 
Emma is the youngest and is never one to back down froma fight. She just wants her family back together. With an evil sorcerer on their trail, it's not going to be easy...
 
Suitable for ages 11+