Picka Bones and his sister, Joy'nt, are looking for something to do with their long lives. The children of Marrow Bones and Grace'l Ossein, they were the childhood friends of Princesses Dawn and Eve, but Eve is married, and they are no longer children.
One night, while Patrolling a Graveyard, Picka and Joy'nt discover three very unusual intelligent animals, a bird named Tweeter and a cat named Midrange need help rescuing their dog friend, Woofer. After they come to understand each other, and Picka and his sister help Woofer out of the place where he was trapped, they share life stories and discover the strange crypt is actually a Think Tank that helps people find ideas. And since Picka lacks the usual skeleton power to rearrange his bones after being kicked in the pelvis, Tweeter thinks that maybe Picka has a different talent- a magical one.
So the two skeletons and three pets go off to find the Magician Humphrey, to find out what Picka's talent might be. They know they will have to work for the Good Magician, but it will be worth it to find out what Picka's talent is. It turns out that Picka's talent is music- he has the ability to make tunes on his own skeleton, by using his clavicles for picks and tapping them on his other bones. Now, normally the Price of an Answer is a year's service to the Good Magician, but Humphrey has a special service in mind for Picka, Joy'nt, and the pets. They must find Castle Caprice, a moving Castle that is so unpredictable in its movements that even the Good Magician can't track it down.
Inside Castle Caprice is the fabled artifact known as Pundora's Box. Like Pandora, it's full of bad stuff, in this case, truly horrendous puns- one that could destroy Xanth in no time. But hopefully, some of the puns that currently infect Xanth could also be returned to the box and make it easier to live there. They set out, accompanied by Princess Eve, who is lonely in her life now that her sister is married, and she has no one to be with.
But Castle Caprice is more than just a moving Castle, it's also intelligent, and is looking for a musician to inhabit it. Once, it had a musician who lived inside it, and used his magic to capture Xanth's more egregious puns and put them back in the box. But the musician's own propensity for chasing girls and indiscriminate loving ended up with him being cursed into the form of a blob. Unable to do his job, he was kicked out of the Castle
But when their party encounters a pun killer named Attilla the Pun, they are forced to kill him when he decides that they must go the way of the Puns. This enrages Attilla's girlfriend, who teams up with the Blob former musician, to take them down. Can the Companions fend off the attacks of Attilla's former girlfriend, find the Castle, and have Picka become its Master, using music to track down the puns and removing the worst of them from Xanth? Or will Piper, who is now dangerously fixated on Eve, kill Picka and steal Eve away, leaving the Puns to permanently infest Xanth?
Xanth has been around a long time, and some time ago, the stories started getting more and more about sex versus love- although it used to be more of the first following the second, and now it's the other way around. In other words, you can tell who is going to end up together in this one, because two of the characters become sex partners fairly early on. I'm not saying that this is wrong, exactly, but it's a big change from where the early books were. The early books were much beloved by teens, as they told stories of adventure, but now, they are more firmly in the adult camp (and to be fair, Piers Anthony has always said his books were meant for adults, it's just that now he's able to bring more of his vision to Xanth.). But I still remember merely embracing engendered a child for Prince Dolph and Princess Electra- no sex needed. So, sometimes, I really have to wonder about this.
Anyhow, being that this is the new reality of Xanth novels, be aware that there is sex in this book. Not just skeleton sex (making babies involves both parents going to pieces with a kick in the butt and assembling children out of some of the pieces), but human sex as well. At this point, I know what to expect, but I still find it distracting to the main story, as much as Piers doesn't dwell on every stroke and thrust, it's still strange to have this mainly an adventure story and in the middle of a chapter have what essentially amounts to: "and they camped for the night. And HAWT SEXY TIMES ENSUE!" Okay, is that really necessary? I don't feel so. It's distracting and occasionally offputting to get this dropped into the narrative. For me, it's the adventure story I really want to read, not how the Hero and Heroine are going at it in the tent when they camp for the night. There are stories I read for romance and sex, and stories I read for adventure. And Xanth, while it had light romance, has always been in the second camp.
This book was mostly good- I liked the adventure parts when they weren't being bogged down by the rampant sex being discussed. I also found it distracting because the characters never seem too tired for sex, they never just lie there and hold each other, or cuddle- it's like all sex all the time, and while it's a strange distinction to make for a fantasy story- it just wasn't realistic in any way that the characters are always ready to bump bones, so it comes off as an adolescent sex fantasy. I'd give it a light recommendation- the bones of the story are good, and the introduction of sex allows the story of Piper's fall to be laid out in detail, but in many ways it's distracting to the story and unnecessary, as well as the whole thing being extremely unrealistic as a relationship.