Su Susu, a senior in high school, is dragged into an endlessly repeating nightmare.
Her deskmate offers her poisoned milk, her roommate drugs her in the middle of the night, and the dean comes at her with a knife.
Every time she dies, she returns to half an hour before her death and has to go through it all over again.
"If you die in the dream, you'll never wake up again."
By dying again and again, she learns the identities of all the killers, only to die at the last moment when her best friend takes a knife meant for her.
When she wakes up, there is no poisoned milk or anyone hunting her in the real world, and even the dean is a different person.
Only her friend Lin Wan is lying in a hospital bed, in a vegetative state.
The truth is more terrifying than the nightmare: there really are ability users in this world who can kill people through dreams.
And Su Susu survived because she has a hidden ability to "roll back" time.
"You're the first person to wake up from a nightmare."
"And the only breakthrough that can counter the Nightmare User."
To save Lin Wan, Su Susu joins the mysterious organization known as the Abnormal Dispute Office.
With thousands of teachers and students at the school, who is the real Nightmare User?
As the investigation deepens, a serial murder case spanning many years comes to light.
And Su Susu discovers that her ability to roll back time works not only in dreams, but in the real world as well.
Theme: Be a good person.
