"Life is always full of coincidences. Two parallel lines may also have a day to intersect..."
Liu Zhikang (played by Tony Leung Ka Fai) is a violinist, Cai Jiayi (played by GiGi Leung) makes a living by translation and writing. The two live in the same apartment building, but due to their different habits - one walks left while the other walks right - they have never met.