Books like The THREAT by David M. Jacobs

Gideon Crew races against time to destroy an alien organism that grew after a failed Antarctic rescue of the world’s largest meteorite, risking humanity’s survival.

When a strange new substitute teacher arrives at a sixth‑grade school, two students discover he is an alien with a sinister plan that could end their class. They must act quickly to save their classmates from an extraterrestrial threat.

A humorous adventure where a group of kids, led by Peter Thompson, encounters three aliens disguised as classmates while the extraterrestrials work on a crucial report that could shape Earth’s future.

"During a live television broadcast on the night of a lunar eclipse, renowned astrophysicist Andrew Leland is suddenly lifted into the sky by a giant spacecraft and taken away for all to see. Six years later, he turns up, wandering in a South American desert, denying ever having been abducted and disappearing from the public eye. Meanwhile, he inspires legions of cultish devotees, including a young physics graduate student named Shawn Ferris who is obsessed with finding out what really happened to him. When Shawn finally tracks Leland down, he discovers that he's been on the run for years, continuously hunted by a secret organization that has pursued him across multiple continents, determined to force him into revealing what he knows. Shawn soon joins Leland on the run. Though Leland is at first reluctant to reveal anything, Shawn will soon learn the truth about his abduction, the real reason for his return, and will find himself caught up in a global conspiracy that puts more than just one planet in danger" -- provided by publisher.

A tense interplanetary expedition turns into a race against a cunning killer as scientists hunt an alien species, but the murderer could be a hostile alien—or a colleague.