Castle Roogna (Xanth, Book 3)

Dor, son of Bink, is a 12 year old magician and next in line to inherit the throne of Xanth. To teach him the skills he will need to rule the kingdom, King Trent sends him through the tapestry on a mission 800 years into Xanth's past to find the ancient and mysterious Zombie Master. Dor travels to the past via the magic tapestry of Castle Roogna and inhabits the body of an invading mundane barbarian. While in the past Dor is accompanied by a (not normally) giant spider named Jumper, who had been drawn into the tapestry with him, and meets his current governess Millie the ghost, a short time before her unfortunate demise. Dor must use his magic and every other resource he possesses to help beat back an invading wave of mundanes and find a way to restore Millie's zombie lover to life back in the present.Turns out the Zombie Master is Millies zombie lover and ends up providing the cure for his own curse.