A cunning thief is desperate to wreck the opening of a historic landmark -- and Nancy is his target! On Gramercy Park in New York City, the magnificent Van Hoogstraten mansion with its priceless collection of glass birds is about to open to the public. Nancy, Bess, and George are invited, but a series of sinister events puts everything in chaos. When the centerpiece of the collection, a beautiful crystal bird, is stolen, Nancy gets on the case. From family members with motives to keep the house, to an antiques dealer with a personal grudge, suspects abound. And when Nancy goes to the family's abandoned camp in the Adirondack forest, she zeroes in on the truth. In a violent nighttime thunderstorm on a solitary lake, Nancy confronts the culprit. The case is solved -- if she can get to shore alive!