Mystery and adventure collide in this humorous and heartfelt multiverse adventure from beloved, award-winning authors Wendy Mass and Nora Raleigh Baskin. Twelve-year-old Piper's life has always been unusual: her parents are clockmakers whose inventions are anything but ordinary, and she's the only kid she knows with a robotic talking dog. But her life takes a turn for the truly bizarre when she discovers her parents are in jeopardy and the key to saving them is a book full of strange equations. When Raisa and Lev travel through the portal to Piper's world, Raisa can finally prove that her mother's multiverse project worked. Now, she just needs the book containing her mother's equations to get back to her world...if only she can find it! As Raisa and Piper adventure to the bounds of the multiverse, they'll need to discover their place in the world if they ever want to find their way back home.