Get a weasel.
We had one follow the mice into the house and the mice disappeared in a week. When I found where they all got into the house I had to make a tough choice- plug the hole to keep out the weasel and hopefully mice or leave it open and only have the weasel to deal with.
Maybe a better choice would be a pet ferret. It is a bit bigger but they will usually return to their cage. Tell your wife it is a rare breed of cat if she is not keen on the idea. Name it Rikki Tikki Tavi.
