From Million-Copy Bestselling Author Si Yi

Inspired by real criminal cases from Taiwan and Korea

Healing Fiction x Detective Thriller

If we could change the past, could trauma and regret be rewritten?

On the morning the phantom sun appeared 12 years ago, Lin Xinyu found her sister's body lying in a pool of blood across the floor. A low-risk victim with no apparent motive and evidence, her sister’s case went cold and her family life shattered in the aftermath. When the same celestial phenomenon returns twelve years later, Lin Xinyu chanced upon an elevator that took her back in time to the investigation room one month prior to her sister’s murder. There she meets Detective Zhang Yan, working on a different missing person case. They formed an agreement to help Lin Xinyu to stop her sister’s murder and to solve Zhang Yan’s brother’s murder.

…but their contact is limited. Time travel could only happen under two conditions: 1) When the phantom sun appears and 2) in the old rundown building scheduled for demolition.

What begins as a supernatural anomaly quickly evolves into a labyrinth of missing girls, domestic violence, cult organizations, and cold cases—all threading back to that blood-soaked morning twelve years ago. Every clue Zhang Yan uncovers in the past sends ripples through Lin Xinyu's present. Every decision she makes echoes across twelve years of anguish and fragile hope. As their investigation develops, everything Lin Xinyu believed about justice, healing, and second chances crumbles.

With the collision of past and present, Lin Xinyu is offered a chance to change the past and fix the future, facing an impossible choice. As the phantom sun rises again, Lin Xinyu must decide: will saving her sister destroy the life she painstakingly rebuilt from the ruins of her grief? Or is the past she’s trying to change already the best possible outcome of a tragedy?

An unexpected detective thriller from bestselling healing writer Si Yi still brings something familiar for all his fans. Simultaneously a gripping detective thriller, When the Sun Divides also addresses the emotional journeys of the lives forever altered by devastating and brutal criminal cases. Whether you’re here for mystery packed investigations or Si Yi’s signature healing stories, you will not be disappointed.