Butler- Tracking Artemis via Shoes

“Artemis isn’t taking
my calls. Imagine that. I think he’s changed his SIM, so I can’t track
him.”
“But we are tracking him, right?”
Butler checked his touch-screen phone. “Oh yes. Artemis isn’t the
only one with Foaly’s phone number.”
“What did that sneaky centaur give you?”
“An isotope spray. You just spray it on a surface, then track it with
one of Foaly’s mi-p’s.”
“Meepees?”
“Mini-programs. Foaly uses it to keep an eye on his kids.”
“Where did you spray it?”
“Artemis’s shoes.”
Juliet giggled. “He does like ’em shiny.”

- The Atlantis Complex, Chapter 8