When you talk to her she'll say she left her bra and panties at her home and wants to get them back. That triggers the "panty snatching quest" . The hidden passage is only for later after you completed the panty snatch quest and got 2 "examinations" with Caroline. You 'll then get another quest to go to the library where the hidden passage is. Then there's a boss fight that triggers when you enter the hidden passage.I tried looking through the topic but I can't seem to find the answer to my problem with Caroline. I'm playing the game via the website Gamcore. It says it's version 0.6.1. Whenever I try to talk to Caroline, she says that that's it for her in this build (I partnered with her and got injured causing the examinations that led to a handjob and a blowjob). In some of the comments however, seems that people are going through the mission to get the lock box etc.
A panty raid quest never showed up for me. I looked and I can go down the bookcase hidden passage, however, I have no statement accepting that quest nor do I know if it's supposed to be pitch black. The guide says something about pillars and I don't see any pillars.
Can i ask have you done everything else with all the other girls ? If not maybe that's the issue otherwise it's probably a bug.