Bonnie Silver has been lured to a mad scientist's laboratory under the assumption that the mad scientist is her father. He wants her to enter the candlestone, which he now has in his possession, and retrieve her mother, who is trapped inside of it. Bonnie agrees to do so only for her mother. When she is transported into the candlestone, she is surprised by the strange surroundings, yet she takes comfort that God is with her. Ashley, a girl working for her father, marvels at Bonnie's faith and immediately feels guilty for ever sending her in. Meanwhile, Billy, Walter, Professor Hamilton, Clefspeare, and Billy's mother are all trying to figure out where in the world Bonnie could have gone and why she left, all while Professor Hamilton is trying to decipher Merlin's cryptic diary.
The setting inside the candlestone is one of the most original fantasy settings ever created. Bryan Davis worked very hard crafting each detail and intricacy of the workings of his original setting. It is not a fantastical setting in which anything can happen and any convenient element can be created to save the characters from harm. It has its limits and flaws, thus making as realistic as it possibly can. Bryan did not spend little time thinking about this; the evidence is clear: he cared about what he was doing when he wrote The Candlestone.
The characters are getting better as the series progresses, as it should be. Billy continues making normal mistakes, and Bonnie and Professor Hamilton begin developing personalities. Ashley, the new character, is a realistic genius character in that she is not very practical. However, Walter and Billy's mother cease to have any purpose in the plot and should have never been introduced.
Besides all this, the end of the book is mostly original. The best part about it is the key character death. The showdown at the end was a bit much, and several other things turn out perfectly. Other than these minor mistakes, the book is flawless.
It is very promising to see that Bryan Davis didn't let the ideas he introduced in Raising Dragons go to waste. He put them to good use and invented several more. I can only wonder what the rest of the series will be like.