Comprising of four girls descending from a lineage of skilled detectives, Milky Holmes boasts exceptional talents known as "Toys". United as a detective squad, their ultimate goal is to gain recognition in this modern age. Rather than relinquishing their Toys and accepting average student identities, they strive to become accomplished detectives. With Kobayashi Opera as their mentor, they diligently apply themselves to decrypt intricate riddles and unravel perplexing enigmas.