haha. I have exactly the same question. Do you go to Fort Street by any chance?
anyway, my teacher said that you can define 'montrous' and 'shadowy, imaginative relm' any way that you want in your essay. So you can say that in gothic, the montrous is fear, violence, monsters, the unnatural, the unknown etc. And the relm can be anything you want as well. So, when the characters don't know what's happening, or when it's all in their heads, or when the audience isn't sure what's going on.