Sonic the Hedgehog Adventure Gamebooks:
Sonic must undo the results of Dr. Robotnik's new invention, a machine which turns good into evil and evil into good.
Is it a bird? Is it a plane? No, it's Robotnik.
It's not unusual for Robotnik to go round messing up the Green Hill Zone. This time, however, he's built a brand-new machine, which turns everything good into bad - even Tails! Sonic faces the fight of his life with his best friends. Will they survive and will he?
Think fast and act quickly - Sonic's going to need all the help he can get!