Who is Janis Langwiser from Chasing the Dime: A Novel and what is their importance?

Janis Langwiser is a criminal defense attorney, who is recommended to Henry by Kaz. Janis works for a small but prestigious firm known as Smith, Levin, Colvin & Enriquez. Their client list is rumored to be so A-list that they aren't even listed in the phone book. Langwiser formerly worked in the district attorney's office, during which time she prosecuted some of LA's higher profile cases. She is described as confident and professional.