The 22-metre-high "Energy Machine" of the Hong Kong Science Museum occupies four-storeys of space, it stands prominently in the centre of various exhibition halls. This huge exhibit demonstrates energy conversion through the movement of balls down the towers. When set in motion, a continuous stream of balls will roll along tracks within and between the two towers like a roller coaster, producing dramatic sounds and visual effects. This video documents the operation of "Energy Machine". By making use of aerial videography, this video presents the ball's wonderful trip from extraordinary point of views.