Shu Yawang (Lu Shan) had tutored Xia Mu (Kris Wu) when he was a child. Now in his adulthood, he realizes that he's in love with her, but she's about to get married to her childhood sweetheart, Xiao Tian (Han Geng). Everything changes when Qu Wei Ran (Joo Won), Shu's boss, rapes Shu while Xiao goes off to serve in the war.
What happens after Shu gets raped won't be spoiled here because that's part of what makes Sweet Sixteen extraordinary. Guy secretly loved girl more than just a friend while the girl is in love with someone else---that kind of plot has been done before, even in the recent remake of My Best Friend's Wedding. What separates Sweet Sixteen from your average romantic drama is that it's not afraid to veer into dark territory while still remaining heartfelt. The plot may seem operatic, but never feels melodramatic or schmaltzy. The love between Xiao and his tutor could have felt creepy and almost feels that way, yet the sensitive screenplay doesn't allow the relationship to be cringe-inducing. In other words, Xiao's longing for Shu feels real and plausible instead of just a plot device. What he does for Shu in the name of love is heartbreaking, surprising and thrilling. Be prepared to be haunted by the powerful ending.