The possums are in the roof. I'm sure there's a large family of them living there. I think there's a gap between the back of the oven and the wall on the other side, and they get from the roof into that gap (it's like a hollow tree to them), and sometimes they fall down a hole and into the cupboard which is underneath the oven. This is the second time this has happened, but the first time I managed to take out the possum unscathed, so I was an idiot and assumed I could do it again.