Campaign help

[TaKaliOmega]

C2 M2 The chase. The princess has been kidnapped. I am chasing the kidnappers and need to retrieve the cowherd. He is being held by a witch, who says she will give him to you in return for a favor. She zaps you into the basement, which you cannot exit. You're to find 3 mushrooms for her.

I have found the mushrooms. They are behind walls which cannot be attacked. I'm stuck in that room. I have killed the monster in it and there are four firetraps and a locked gate to the south.

Is there something I'm not seeing? Something I'm missing? Literally can't continue because I can't exit that room. It seems I'm supposed to get the mushrooms, but there doesn't seem to be any way to do that.

Thnks in advance for any help.