She's back in her tub, and it's secured. I ended up buying a live rat and placed it in a critter keeper next to the fridge. After an hour, I checked under the fridge and she wasn't there. The thing was, I wasn't sure if she was somehow inside the inner workings or if she'd left the area; the flour I'd placed around it didn't seem to be disturbed. I ripped the kitchen apart looking for her. It'd only been an hour; she's not that fast and couldn't have gone that far. I found her behind some cabinets and had to use a coat hanger to pry her out. All is well now.