Napier Incorporated is the business Jack Napier starts in Finance & Felony - The Movie together with his niece, Diana Napier.
The Napier Inc. is trading in goods, from medical supplyment to luxury goods like exclusive clothing and/or jewelry. As it is located in Los Santos, they have to deal with criminals trying to steal the goods all the time. What's worsening it, is that Howard Pacone has also started a business, Avenger Corporation. The two businesses are in direct competition.