Use the robot mouse in the basement to obtain the key that was dropped. The mouse is usually controlled with instructions such as "Mouse, go east" or "Mouse, go west". However, the mouse is unable to hear you once it enters the hole in the wall. To continue, speak commands to the hole instead of to the mouse, such as "Hole, go north" or "Hole, go south". Give the directions to the mouse by speaking to the hole, and the mouse will hear you.