Watch out for the plesiosaurs!
There are not enough middle grade books involving dinosaurs, so this is a great addition to the list of dystopian adventure novels. Since Sky was raised in an underground compound and Todd was raised topside, we get to see a range of reactions to the conditions that they see in the East Complex. I love all the details about the computers, electricity, and even the uniforms that the inhabitants wear. The details of the Lincoln Lab, with its setting in the middle of the lake and it's security detail of plesiosaurs was fascinating as well.
Sky's continued attempts to find her father or people who knew him are endearing and wistful, and the help she receives from her grandfather is nice to see. Chaz is a fun addition to the group, and sensitive fans of Shawn should not be overly worried about his disappearance.
Any aficionados of dystopia will want to add this series to their to-read list, and readers who enjoy rich, futuristic world building found inbooks like Perry's The Scavengers, DiTerlizzi's The Search for Wondla or Blakemore's The Firefly Code will enjoy their brief but exciting sojourn in the Lincoln Lab, East Complex and the new East Settlement.