Now don't get me wrong, The 39 Clues is my most favorite book series of all time. I have read 19 of the main books, and just today bought the 21st book so I can get it autographed at the book festival next week. I like the series so much that my 3 favorite books in general of all time are all from this series.

However, even though I love this series so much, I think that the publishers are taking it too far. The first series, which was pure epic and only had 10 books finished back in 2010. Everybody was so happy to see how it would end, but then Scholastic announced that there would be an even better 2nd series. The first series was very long, and ended up finishing with 11 books, a few side books, and 7 ebooks, but everybody was super happy that the series would continue.

They were right though, the 2nd series was even better, they were able to condense all the action and suspense of the 10 books from series 1 into 6 books, which is still quite long. March 2013 came along and everybody was hyped about the final book because there was much more drama and suspense in that one book than the entire first series, but then Scholastic made it seem like even more stuff could happen by adding a third series.

Instead of being all, woooooh, like I did after the 1st series, I was meh this time. I told myself this that it couldnt get any better. I was wrong though, the first book of the 4 book series 3 was even better than any of the others in my opinion, but it's as if you could feel pain in the book. As a fan, you know what the characters have gone through and you just want it to end. I read books 1 and 2, and I bought book 4 today in the hopes it would be the all powerful final book that I would get autographed and keep forever, and then on the last page of the book, there's a design.

Each book of course, has it's own cover design, and each series has it's own logo style, so when I first saw that design, I knew that there was going to be a 4th book before I even checked online. It was a new logo design I have never seen before, and when I finally checked online, it was confirmed that there's a 4th AND FINAL series coming out next year.

If this was a series like The hardy Boys, where each book is a random story with no relationship to the other, I would be fine, but this is not like that. Each book, even books from the other series, are a direct contininuation, and when you do that, you have to end at some point, and I feel that they should have already ended. Again, don't get me wrong, it's not like they ran out of ideas or their ideas are getting stale, it's just that they put in so many ideas and after each one they have a nice way to finish it off, but theydon't, they keep going on and on, making it even more dramatic for the people reading because they have more things to worry about.

Sure, the 2nd series was great, but when the 1st series ended, I thought I was out oft he clear, that everything bad had happened already, and then when the next series was announced, you already start thinking about all the bad things that can happen, even months before the book is released. After the 1st series ended, it got to the point where good things don't happen anymore, the only excitement from the later series is the main characters stopping the bad stuff from happening in the coolest of ways, but other than that, more and more people die who you would have thought were safe, and everybody is torn apart.

There are other fans of the books out there, right? What do you think of this?

I understand your pain. They're trying to squeeze every penny out of the series, and for the readers it's terrible.

And while I can't think of any particular book series where this happened, I know it happens all the time with movies and TV shows.

It's not unnatural to see one book to take up multiple movies these days, when it would have done just fine as a single release. Several TV shows get uninspired or change so much in later seasons that I just don't like watching them anymore. =/

zanderlex : Correction: They did backstories for the characters. What I meant was maybe after a few years someone else had to undertake some kind of impossible task that had something to do with the Cahill family. Sidebooks?
Meh. I like Percy Jackson more...

steel_attacker : Sidebooks? There's 15 sidebooks.
Most of the sidebooks have nothing to do with the same characters from the series, but new characters from many years ago.  
http://the39clues.scholastic.com/cahillfiles 

That link goes to the Cahill Files, a series of 5 books. The first 2 books involve some of the characters when they were young, but the last 3 are all from the 1700's and 1800's.

Now that there's going to be a 4th series, that nobody knows how many books there will be, or how many years it will last, there's going to be an opportunity to write even more sidebooks.