“You’re got to be very careful of the open sky,” Tugu said. “Step out in the open, and they’ll have your position in ten to twenty seconds.”

“Satellites?” Richard said.

“Yes. Anything line of sight will give them a lock, and fast.”

Richard felt sweat prickle along the back of his hands. “What about inside? Or in a car? Hell, this tree can’t be much of a shield.”

Tugu nodded. “Cover only delays the lock. Doesn’t stop it. Stay in any one place too long–twenty-four to forty-eight hours–and they’ll get a lock. Once that happens…well, I’m sure you can imagine.”

“Can’t we get the tag removed?” Richard said.

“Surgery takes time, and you’ll more than likely be caught by then. Of course a few people have tried, but it’s tied into your central nervous system in a rough way. Most of the time, if you’re lucky, you’ll be quadriplegic. If you’re lucky.”