Last week I put out mouse poison. The day after I put it out, I found a dead mouse in my hallway. Today, I went into one of the rooms where the poison was and there was the dead mouse smell, but no dead mouse. I'm assuming it's in the wall? How do I find out where it is and how do I get rid of it? I'm afraid the smell is going to attract bigger and badder rodents.

I would look carefully under and in things - anywhere a mouse could hide. Then, look behing the plates in electrical outlets. If you can't find it, you can be pretty sure that the smell will go away in a couple of weeks. I doubt you need to fear larger critters coming after the dead mouse.