Vanished: Books Three & Four

From Author Wars - https://authorwars.com/books/vanished-books-three--four-1484992.html

Overview:

Title: Vanished: Books Three & Four
Author: Meg Cabot
Year: 2011
Type: Omnibuses
Series: 1-800-Where-R-You

Variant Titles:

2011. Vanished: Books Three & Four