Lucy, The Mad Scientist!

The story would start with Lucy setting a chemical/alchemical trap that shrinks characters that then have to deal with a woman/futa that is now the size of a giantess to them even though she is a normal-sized woman. The main goal would be finding a way to escape her house and return to normal size. Or, learn how to enjoy what Lucy has in store for them and live the rest of their live(s) as a tiny.