Until the mid-1970s in all the old sections of the cities of Spain there was a man who walked the streets at night from 10 PM to 6 AM with a ring around his neck on which there were a large number of keys. When a resident came home ar that hour he was without the key to his portal and the portera was off duty. He would clap twice and the man with the keys would appear, open the door for him, get a few pesetas and disappear into the night. He was called the Seréno. This is the story of his life, going back in time over 60 years, with an authentic historical background of strife, epidemic, civil war, and dictatorship.