A photo journalist's quest for precision can go so far that it is hard to tell whether the human has become a machine or the machine has acquired a desire of its own. Cheung and his beloved Leica managed to captured a moment between life and death; the gaze from the subject haunts Cheung so much that he loses the strength to take another photo. Based on the true story of the famous photo journalist Mr. Lam Kai Cheung, The Decisive Moment reconstructs his life aided by interviews of his colleagues. The intriguing relationship between the object and the subject is brought forth for philosophical reflection.