Struggling detective Satoru Kido is lured to a remote island by a mysterious letter requesting his help to find a missing family heirloom: a rare ruby ring known as "the blood of a phoenix." Upon arriving at the Nakakouji mansion, Kido encounters the unstable mistress Ayano and the timid maid Nozomi. As he discovers hidden passages and navigates the mansion's erotic and psychological tensions, he realizes the case is far more complex than a simple missing item search.