Sonambulo was a famous masked luchdore of the 1950s, a star of Mexican cinema and a main event competitor in the rings of lucha libre (Mexican wrestling). His luck began to change for the worse in 1959 when he was suddenly stricken with a strange sleep disorder. To compound his difficulties, a crooked wrestling promoter/mobster by the name of Jack Molano showed up in the locker room after one of Sonambulo's matches to demand Sonambulo join his organization as an enforcer. Sonambulo turned the offer down flat. Despite the warnings of his friend, The Jersey Devil, Sonambulo wasn't worried about Molano and his cohorts and went about his business.
Later that night, one of Molano's thugs shot Sonambulo in the back as he attempted to leave the now-empty arena. Molano had two of his men stomp and beat Sonambulo to near-death and shove him in a wooden crate. Believing Sonambulo to be dead, Molano then instructed his men to stash the crate under the floor beneath the ring. That is where Sonambulo would lie unconscious for over thirty years.
Sonambulo finally regained consciousness and broke free from his makeshift prison. Soon after he came to realize that he had lost the ability to sleep and could not lose consciousness. He has literally been wide awake since that time. In addition, he had acquired the ability to look into the dreams and nightmares of anyone he comes in contact with at any time he so desires. With thirty years gone by and his wrestling career obviously behind him Sonambulo decided to parlay his unique talents into the private investigation business.
Now, with his trusty secretary/assistant/sidekick Xochti he runs the Nocturne Investigations agency. His work has led to encounters with mummies, zombies, the undead, a cult leader bent on resurrecting silent film star Elsa Lemper, and many more ranging from the mundane to the insane.