In order to find more about Chu Nen's death - and probably to avenge her, since she was Lin Yan's love interest, judging by the flashbacks), whose murder became a cold case, Lin Yan joined the police force to try to investigate on her on, whatever it takes. Then, she met Song Yohuan, a tight-laced cop who follows the law and order to a T.
Afraid of having her motives uncovered, Lin Yan decides to do things on her own during the cases, even if it means to get in the way of the police, but she makes Song Yohuan even more suspicious of our Miss Forensic. Meanwhile, both realize they are developing feelings for each other, albeit in a love-hate kind of relationship.
Did I get it right so far? I must confess I'm a bit confused myself with the development in the latest chapters.
Like, if Lin knew Li Shiping were going to murder Ding Xue, because he was Sun Xiangming's (her girlfriend) murderer, why did Lin intervened by killing Li in the first place? Did she feel sympathetic towards Li and didn't want her to be sentenced over a passional crime?