Where do I get a file

Hint 1 of 11:

Still didn't listen to the man in the jail?

Hint 2 of 11:

Go to the jail and give the guy something that he wants.

Hint 3 of 11:

Something close to what he wants will do.

Hint 4 of 11:

He's been trying to get rid of rats, right?

Hint 5 of 11:

Check you inventory - do you see anything new?

Hint 6 of 11:

You do have some kind of rodent repellant, don't you?

Hint 7 of 11:

Give the prisoner the gopher repellant.