When Nancy and her friends attend a Mardi Gras ball at a so-called haunted mansion, George brings along a digital camera to catch some ghosts in action. When freaky things start to happen, the guests begin to wonder if the ghost stories could actually be true. But when Deirdre Shannon's antique tiara is snatched, Nancy is pretty certain the crook isn't a ghost.
When George's mom asks Bess, George, and Nancy to help her cater a benefit for the library, everyone agrees. The event is a Jane Austen-themed tea party, and George even agrees to wear a dress for the occasion! It seems like the party isn't everyone's cup of tea though. The bed-and-breakfast where the event is being held has been plagued by vandalism. Someone is breaking teapots, making a mess, booby-trapping the staircase, and generally terrorizing the old couple that towns the place. No one can figure out how the intruder is getting in and out of the house - and that's when Nancy gets to work!