Benjamin, I just finished an adaptation of a book, but accomplished it in a not-so-usual way. The book had just made the NY Times Best Sellers List when I approached the author. His line in the sand was he wouldn't give me the rights... he wanted to write it with me. We both took a huge leap of faith in each other and dove in. I'm not sure I'd recommend everyone to write with the author, because many can be rigid about changing their original story, but I was lucky. The author I worked with was generous, and gave me more freedom and trust I could possibly have imagined. If you already found a book, I suggest a light "stalking" of the author to see if you think your personalities might mesh and throw writing it together on the table. He still owns the rights to the book, but we jointly have the rights to the script. Didn't cost me a dime... but I put in tons of sweat equity. Good luck!

I wrote an adaptation as one of my first ever projects, but I didn't tell the author or seek the rights. I just did it for fun and experience. One day I might contact the author. It's not a book that anyone outside of a very specific crowd would know. Very local.

Similar to TT - I have done an adaptation of a book to which I don't own the rights. Partly because I had to get the script out of my system, it was haunting me :-)

However I do know that (a) the rights are available and (b) I could get them because I have spoken to the agent.

But I'm in no rush and the script stays with me until I'm in a position to move with it.

Generally though I agree 100%: it's not a good idea.

I should mention I found the author via his website for the book. His contact information was right there. But, I have also found authors by calling their agents. If there's a way to get to the author directly though, I prefer that. One less gatekeeper. All it takes is a little research and guts to pick up the phone. If not you, someone braver will do it.