When wounded soldier Robert stumbles into a mysterious castle during a storm, he finds himself captivated by its beautiful and enigmatic mistress, Greta. Behind the castle's ancient walls lie secrets beyond imagination - servants that aren't human, rooms that appear and disappear, and technology that seems more magic than science. As Robert and Greta grow closer, he discovers she harbors a devastating once a month she transforms to be trapped and tortured by the very castle that protects her. Their growing love may be their salvation or their doom, as dark forces gather to claim Greta for sinister purposes that span worlds. Together, they must unravel the castle's mysteries and face dangerous truths about Greta's origins before their sanctuary becomes their prison. But can love forged between a soldier and a monster survive when ancient powers come to collect their due? A spellbinding blend of romance, fantasy and science fiction that questions what it means to be human in a universe far stranger than we imagine.