Sam Fisher- Homemade Motion Tracker

  FISHER was awoken by the cricket chirp of his iPhone. Having set the ringtone to match only one incoming number, he knew the alert meant visitors had arrived. He checked the time: 11:15 P.M. He sat up in bed and looked around, momentarily confused by his surroundings--the by-product of moving around so much. The decor and layout of chain hotel rooms tended to blur together.

  The good news was that the visitors weren't his but rather Boutin's. The night before, Fisher had planted a homemade motion detector around Boutin's apartment door: the tremble sensor from a vehicle's antitheft GPS tracker wired to a prepaid cell phone. The tremble sensor was buried beneath Boutin's doormat, and the cell phone buried against the wall a few feet away, its antenna jutting up among some weeds. Lacking the technological edge that working for 3E had provided, Fisher had, during the last year, become a fair inventor.

- Conviction, Chapter 3