And cats help us how exactly?

Maybe that title is a little passive aggressive. Maybe it's my fault. I brought the boy kitties home from the vet today and shut them in the laundry room to give Miss Natasha a chance to explore the upstairs for the first time. She spend 40 minutes in the bedroom. Then I watched her go into the living room, where she promptly disappeared. I have searched the upstairs several times and find no sign of her whatsoever. Spooky. Had to let the boys out for their dinner, and I figured she'd pop out and hiss at them as she seems to like to do, but there's no sign of her anywhere. Ulp. I lost the cat. Oh no! Now what do I do?