And God Remembered Avraham, and He Sent Lot” – Behind the Scenes of the Rescue in Sedom

Even though God had already decided to destroy the cities of the Plain, He reveals His intentions to Avraham before He actually executes His plan. Once Avraham hears about the plan, a discussion develops between him and God about the necessity of executing the punishment. Lot, Avraham's nephew and a newcomer to Sodom, is not mentioned in this dialogue. Why not? And what does Avraham's argument accomplish?