Design concept: due to the high density of residential buildings in Taiwan, people usually install iron or aluminium doors and windows on their home balcony or windows and have a habit of locking them all together with the small emergency exit. This practice, despite protecting house and home, has many hidden risks. For example, many tragedies have occurred in fires or natural disasters when people couldn't find the key to the emergency exit. To avoid this, we designed the Hidden Hook, which can be placed close to balconies or windows. Although it looks like a common hook, inside it is the key to the emergency exit, with no worry of it being found by burglars. The hook cannot be easily opened from outside the iron doors/windows. The design is simple and elegant, and can be easily placed close to windows or the balcony, which makes it safer.