Angel of Fire: Book One of Zach's Story (Third Edition)

Zach Brinkley is in hospital, unable to talk to anyone except some bizarre, otherworldly visitors. These include an annoying "winged thing" and a set of spooky twins. It's the twins who explain to him that someone is trying to kill him. Can Zach, with the help of his otherworldly friends, turn the tables on this would-be killer?