Criminal profiler Shen Tang takes over the "Perfect Secret Room Case": Her husband Lu Jin has an impenetrable alibi, and all evidence points to the deceased committing suicide. Until Shen Tang turned out a page of the diary that was blurred by water stains, and it said, "He smiled so strangely today." Lu Jin laughed on the spot and admitted that he had killed someone, but the next second he revealed an even more shocking secret - this was just a scapegoat, and the real murderer was someone else. Shen Tang and detective Zhou Yan must uncover the lies within three days, otherwise Shen Tang himself will be the next target. And that page of the diary is connected to Shen Tang's father, who has been missing for ten years.
