In the fourth volume of the New York Times bestselling Books of Elsewhere series, Olive thought she had uncovered all the house's secrets. She was wrong. It's Halloween night when strangers come to Linden Street . . . and something absolutely vital to Olive goes missing. To what lengths will she go to get it back? Can she trust the strangers? Will she turn to a new and dangerous magic within the paintings of Elsewhere? Or will Olive put her faith in her own worst enemies to save the people and home she loves? The stakes grow higher, the secrets more dangerous, and mystery and magic abound as Olive, the boys, and the magical cats uncover the true nature of the old stone house on Linden Street. A must-read fantasy series for fans of Pseudonymous Bosch, Coraline, and Septimus Heap.