The Area 51 Files: Friend or UFO by Julie Buxbaum (The Area 51 Files #3)

Sky’s life in Area 51 is full of surprises. Like the fact that aliens are real—and now one is her best friend! But the biggest surprise yet comes when Sky learns that her grandmother has been kidnapped and is stuck in Area 52, the only other alien portal on Earth. Even more bananas? Her grandma has been an undercover FBAI agent for YEARS. Like Sky’s whole entire life. How could Sky not have known her grandma had a secret identity?

Uncle Anish says to leave this whole mess to him. For reals this time. The kids just have to hang tight. Spoiler alert: The kids do not, and will never, hang tight.

There’s just one problem: No one knows the location of Area 52. In order to solve this mystery and save Sky’s grandma, Sky and her friends will have to solve a series of secret puzzles and codes, traverse the Area 51 library for clues, break into FBAI headquarters, and more. But someone doesn’t want Sky to solve this mystery, and they’ve got their eyes on her…