Magic Grandfather, The (Vintage Paperback) by Jay Williams

Sam can't believe it. His own grandfather is a real magician--and not just magic tricks, REAL MAGIC!!

Now the old man is summoning some strange beings from another world, and he's warned Sam: There must be complete silence. The room begins to glow...it swirls with color...the spell is working...

Instantly, there's a loud popping sound, and his grandfather disappears! He's been zapped into that other world--and it's up to Sam to get him back. But can he? Can he really reverse the spell?