The lost colony - eoin colfer

Until recently, Artemis Fowl was the only human to have discovered that magical beings do indeed exist.

But now a second juvenile genius wants to capture a demon for scientific study.

Only an ancient time spell separates the demons from humankind--and Artemis must prevent it from unraveling.

If he fails, the bloodthirsty tribe will relaunch their quest to wipe humans from the planet.