You first need to capture Violet and talk to her to learn about the secret passage.
It's probably a bug because you should be able to talk to Violet even if you're not fighting Aria.
But I checked the game and it shouldn't be possible to have a situation where you can't talk to Violet... Did you use the save data from the previous version? Please give me some time .I'll release 0.4.0.3 with bug fixes tomorrow.