Title: Trial and Error Introduction: On August 12, 2019, a large number of demonstrators gathered at Hong Kong Airport to protest the police's excessive use of force, demanding "Return the eye, black cops," and reiterating the demands of the anti-extradition movement. Bruce Lee's famous quote "Be Water" was revered as the movement's philosophy, opening a new mode of social movement in Hong Kong. As news of the police clearance spread, facing the possible tear gas and arrests, the demonstrators had to find a way to retreat like the tide and evacuate safely.