Christopher Bulis is well-known inside the Doctor Who mythos as an author who writes very traditional Doctor Who stories. There won't be any radical characterization, no big changes in the Who universe, or anything like that. His characters are usually one-note and it's his plots that either make the book worth reading or not. Thankfully, Palace of the Red Sun is one of his better ones.
The TARDIS lands in what seems like an idyllic garden setting. The red sun beats down on it without much heat, giving a very pleasant atmosphere. The Doctor and Peri decide to stay and have a little bit of a holiday. The Doctor, however, is intrigued because he can't get the TARDIS controls to tell him where they are. Peri decides to wander around the garden a bit, and is met by a talking bear with a hat (think Paddington). This bear wants to play a game, and ends up leading her into a pit that's impossible for her to get out of. The Doctor goes to get a ladder, but when he comes back, Peri's gone!
Meanwhile, Glavis Judd, the self-proclaimed protector of the galaxy, has invaded the planet of Esselven to rid it of its supposed tyrants. Unfortunately, the royal family manages to get away, and leave all of the governing documents in a vault that can only be opened by the DNA signature of a royal family member. Judd spends the next year trying to track them down. The intrepid news reporter, Dexter Dynes, has been following the story from the beginning, hoping to get lots of exciting (and violent) news footage. When Judd thinks he's finally tracked them down, Dynes couldn't be happier.
What do these two plots have to do with each other? The story becomes a race against time as the Doctor tries to find the "Lords" of these gardens, and tries to save them against an invasion that they don't seem to realize is coming. Peri has to deal with the people who live outside of the gardens. Who can they trust, when nothing on this planet is what it seems?
The plot behind Palace of the Red Sun is actually very interesting. The two plots initially don't seem to have anything to do with one another, but Bulis does tie it together well. The idea of a "Protector" going around and invading places for their own good is kind of interesting, though it doesn't seem that realistic, especially as Bulis presents it. The idea that numerous worlds could see what Protector Judd has done to other worlds and still want him to "save" them is, to me, a little ridiculous. I know that some people would welcome it, but this many?
The relationship between the garden idea and this militaristic plot is very intriguing, though. Bulis does make the transitions from one to the other very well. The Doctor and Peri are hard-pressed to figure out what's happening. The plot has a certain "what the heck is going on?" element to it that is not always done well. Here, it is. Just when you think you've got it figured out, Bulis throws a bit of a twist in. The final couple of twists are really interesting, though, as the two plots dovetail rather nicely and are finally resolved.
It's too bad the same can't be said of the characters. This has always been Bulis' weakness. The characterization of the Doctor and Peri are passable, but that's because we have numerous books and TV episodes to keep in mind as we're reading the book. The original characters suffer a great deal. Judd is a ruthlessly efficient tyrant who will do whatever it takes to achieve his goals. Dynes just wants the story and to have as much violent footage for his broadcast as possible. There is a "robot starts becoming sentient" bit that is straight out of many science fiction ideas (though the robot is one of the more interesting characters in the book). The inhabitants of the garden fulfill their assigned roles, but do little else (though there is a bit of a reason for that in story terms, I won't say what it is). Basically, they're all very bland and uninteresting.
Dynes is a character from one of Bulis' previous Who novels, The Ultimate Treasure. There really isn't any reason for him to be in this book other than at the whim of the author. Bulis tries to make a point about how the public seems to lap up violent news images even as they decry the media for broadcasting them. However, the point is so heavy-handed that my head hurt from the mallet Bulis hit it with. It's too bad, too, because Dynes certainly seemed to have potential as a worthwhile character. However, in a Bulis book, there are no shades of grey, which always make the best characters.
Thankfully, though, the plot is intriguing enough to make up for it. This is a very lukewarm recommendation, but ultimately I would recommend the book. I don't think I would make it your first Dr. Who book, though.