The movie "So Close," written by Jeffrey Lau, is about a pair of sister assassins who quickly find that their blood relationship is a conflict of interest in their cut-throat profession.
The sisters, Lynn (Shu Qi) and Sue (Zhao Wei), are in possession of their late father's secret satellite technology, which gives them the upper hand over their enemies and the law. Sue is the assistant. She's almost always at home in front of the computer. Lynn is older and the better assassin, so she spends her time in the field. The girls secretly spread a computer virus to the network of a high-tech corporation. Lynn, under the guise of "Computer Angel," is asked to fix the bug, but when she's granted a meeting with the CEO, he quickly becomes her victim.
Their mission is accomplished, but a police detective named Hong Yat Hong (Karen Mok) is quickly on their trail. The chase is really on when Lynn and Sue become the targets of the corporation that initially hired them. Meanwhile, we can see that the sisters' working arrangement has made Sue jealous. She wants to do assassin work, but Lynn keeps her busy at home to protect her. Lynn's decision to marry her love interest and give up the assassin life causes a rift in the girls' relationship.
Sue decides to continue contract killing to prove herself to Lynn. Yat Hong tracks Sue to a bakery, which leads to a high-speed car chase around the city. Sue finds herself cornered and at the mercy of the police, so she calls on Lynn for help. Meanwhile, Lynn has been tracked down and killed by the men that first hired the girls for the assassination of the CEO. Yat Hong is framed for the death.
Sue offers an olive branch to Yat Hong. She can help the detective clear their name, but only if Yat Hong agrees to help avenge Lynn's death. A desperate Yat Hong joins with Sue and finds Lynn's real killers.