Dive (2017)

Nanshan, a high school student, reunited with his mother after a long absence. The mother has been very busy with defending her rights, and her attitude towards Nanshan has been very indifferent. Nanshan isn't able to help her mother nor get her mothers lover.In an accident, Nanshan's mistake caused his sister to drown. After blocking her mother's most important rights protection activities, he tries to use sister's drowning to blackmail the owner of the swimming pool. Is this a way for him to keep his mother?