We learn about Doc’s previous career as a skip-tracer—someone who locates a fugitive, such as a debtor, who otherwise can’t be found. He worked for a firm called Gotcha! Searches with Fritz Drybeam. We also learn the origin of Doc’s nickname.
Doc visits his old office and Fritz shows him the firm has access to ARPAnet, a forerunner to the Internet, and suggests it might be useful in determining Shasta’s whereabouts.
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Character Relationships in Inherent Vice, Chapter 4 — 117 KB PDF