Found: I would be really thankful if you could help me.

I once remember reading a book series when I was younger about a group of kids(I believe 3) who find a door to another world(A fantasy world). This world has all the fantasy stuff obviously. One thing I remember is that one of the protagonists is brainwashed using magic by the antagonist and becomes an evil prince. Not sure about the name but It could have been prince Eric.
Thank you so much.

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The Secrets of Droon by Tony Abbott

>3 HiBooks: Thank you so much, I was thinking about this book series. recently and forgot the title.