Su Wan received a red envelope from an unknown source every night at the funeral home, with the only postscript saying 'thank you'. She thought it was the gratitude of the family until forensic doctor Zhou Yan discovered that these deceased people had all appeared on the same list of missing persons. Aunt Lin's lamp, Chen Xiao's transportation bill, and Qin Yutong's poems reveal a black market for organs under the cover of 'gratitude'. As the number of red envelopes increased, so did the deaths - and Su Wan finally realized that the next person to be 'thanked' might be herself.
