“It’s my mother, Butler,” he said at last. “I’m beginning to wonder if
she’ll ever—”
Then the proximity alarm flashed red.
...

Butler checked the porta-radar, muting the volume in case the
equipment betrayed their position. The red arm swept the screen with
agonizing lethargy, and then . . . flash! An upright figure by the tree. Too
small for an adult, the wrong proportions for a child. He gave Artemis the
thumbs up. Possible match.

- Artemis Fowl, Chapter 4