The Magicians Nephew: Graphic Novel by C. S. Lewis
The second of C. S. Lewiss novels to be produced in graphic novel style, The Magicians Nephew is actually the first in the Chronicles of Narnia series of seven titles.
Polly and Digory meet one day over their garden wall. They decide to explore the attics above their houses one wet summer afternoon, and by mistake come across Digorys mad Uncle Andrew in the middle of an experiment. First Polly, then Digory, touch the magic rings which take them out of our world and into another one, where they encounter the evil Empress Jadis and by mistake bring her back to England. In a desperate attempt to get her away from the havoc she causes in London, the two children magic her and several others into a totally different world the world of Narnia.