In life, Belaric Marcosa was a wealthy man who surrounded himself in luxury. He lost his right leg under unrevealed circumstances and had it replaced with a wooden prosthetic carved to look daemonic. He also had rubies set in his two front teeth. Marcosa hosted large gatherings in his house, most drawn by either his affluence or his reputation as a faith healer. Unfortunately, after he tired of their company, he used his house as a medium for his supernatural powers and drove his guests to slowly go mad and kill one another. Among his victims was a magician named Gideon Blaine, whose soul he bound to the house to strengthen its powers. 47 people died in Marcosa's home before his physical body died.

Post-Death

Another wealthy man, Jerome Selwin, was convinced that Marcosa House held the key to prolonging his life. Diagnosed with cancer, Selvin hired a group of psychic researchers--including Steven Marston and his wife, Elaine--to investigate the house. Six of the research team, including Steven, died as a result of their experiences. Elaine survived but escaped the house in a fugue state. Eventually, she regained much of her memory. A year later, reporter Buck Cowan interviewed Elaine, believing Marcosa House also held clues to end the generational lycanthropy suffered by Jack Russell. The two developed feelings for one another, but during a romantic weekend at a ski resort, Cowan was left in a coma after being attacked by Russell in werewolf form. In a lucid moment, he mentioned Marcosa, and so Elaine, Russell, and their allies, Lissa Russell and Topaz, went to Jerome Selwin and then the house itself to investigate. Like the research team before them, they encountered Marcosa's spirit. The dead sorcerer tortured them using ectoplasmic projections. Blaine's spirit, interacting through Topaz, guided them--and Cowan, who had recovered enough to drive himself to the house to help--to the location of Marcosa's final resting place. Russell destroyed his skeleton with a sledgehammer. Marcosa has not reappeared since.