From the Chaosium website:
Modern-Day Non-Player Characters
This is a collection of 120 Modern Era NPCs for overworked Keepers to use in their games and campaigns. These NPCs are ones typically found in society and can provide useful information, assistance, or adventuring opportunities for Investigators. All are complete with Statistics, skills, a physical description, and a brief, but highly individualized background that can be placed into any Modern Day setting. The collection is organized by 15 Occupation types, each with eight NPCs.
Keepers can place these NPCs in pivotal roles in a scenario; they may be used to provide a specific service to a group of Investigators (medical treatment, fabricating an item, research, etc), be given out to individual investigators as personal contacts and act as the basis for a scenario as an information-seeking Patron for the Investigators or simply being a witness of Mythos activity or a relative of a victim seeking help from the Investigators. They can also act as plot drivers when Investigators naturally stray from the prescribed course of action.
If an investigator is seeking a speaker of some uncommon language, several of the collected NPCs have unlisted language skills; Keepers may feel free to plug in any desired language required for the occasion. Keepers are welcome to modify the NPC in any given way; name, nationality, languages spoken, weapons on hand etc, to better suit their campaign’s need.