Speculative fan fiction for the upcoming horror game The Callisto Protocol. Daniels has been sentenced to Black Iron Prison, a penitentiary built onto Jupiter's moon Callisto. After a few miserable months, he suddenly finds himself in a unique position: as a professional diver, he is tasked with diving into the mysterious Stygian Sea the prison is built near and recovering... Something. Something he can't know the truth about. Something he can't speak about. Ever.