Okay, I'm currently in the River Dungeons, dealing with the tentacle books. I find books 1-3 just fine, but every time I want to head west I keep getting the "next book is south" dialogue. I've already done book 3, with the slime girl, but I can't find where I need to go to find book 4. I've looked everywhere, pressing the player to every wall/tree/plant I could see, to see if there was any hidden pathways I hadn't found, but nothing. Looking into the "walkthrough" doesn't help, since it doesn't give direction on where to go or what to do, just about what you'll find.
Can anyone give me some proper directions from the 1st book to finding book 4?