Mei Arellano does not remember her real past. She only knows that ten years ago, she was found and adopted by a kind but simple family, gave her a home, and raised her like their own. Lumaki siyang masipag, puno ng pangarap, at hindi sumuko sa buhay. Now, she finally earned a scholarship to Northvale Academy, the most prestigious school in the city. But there was one thing she didn't expect-napasama siya sa Mystery Class X, the most secretive and infamous section in the school. Kasama niya rito ang apat na lalaking kilala sa pagiging mayaman, gwapo, at sikat... pero may tinatagong misteryo. As Mei steps into their world, strange things begin to happen. Shadows of the past start whispering to her, pulling her closer to secrets she can't remember. Sino ba talaga siya? Bakit parang may kulang sa buhay niya? What if this school was meant to lead her back to the truth? And what if the truth is something she's not ready to face?