In an era when time travel experience has become the top luxury consumption, after-sales specialist Xiao Yan faces customers every day who are immersed in the dream of another world and are crushed by reality. Until she received a special customer, Gu Shen - this man refused to disclose any experience and feelings, and was so calm that he was incompatible with other customers.
Xiao Yan accidentally retrieved the background data and discovered that Gu Shen's destination was the empty space and time numbered 01210121 - a recursive trap that theoretically did not exist and was permanently banned by the system. In the record, there was only a mirror in the void. What was reflected in the mirror was not Gu Shen, but Xiao Yan himself who was checking the record. An infinite recursive closed loop with no beginning and no end entangled the two of them.
As the investigation deepened, Xiao Yan uncovered the company's secret "Mirror Project" three years ago, and learned that Gu Shen's trip was to find his father who was trapped in the mirror ring. After the plan got out of control, Gu's father voluntarily entered blank space and time to suppress the crisis. Not only has the headquarters not terminated the plan, but it has also restarted research in secret. Behind the scenes is the mysterious organization "Eternal Society", which attempts to use the mirror ring to devour human consciousness to achieve immortality.
Xiao Yan and Gu Shen join hands, using the pen engraved with the number 0121 as the anchor of time and space, to fight against the pursuit of the headquarters and the Eternal Society, and go deep into the wreckage of the alien spacecraft on the seabed to explore the truth. When the mirror ring crisis spreads and the barriers between mirror people and real humans gradually collapse, Xiao Yan discovers that he is the "balancer" connecting dual time and space. Every decision she makes with Gu Shen will determine the ultimate fate of the two time and space.
