"HE OPENED THE RED DOOR"; YOU SEE, BY USING THE WORD "RED" THE WRITER WANTED TO EXPRESS ANGER AND FRUSTRATION. ALSO, THE ACT OF OPENING IT INDICATES THAT THE CHARACTER IS PASSING FROM ONE WORLD TO ANOTHER, IN THIS INSTANCE HE'S PASSING FROM THE OUTSIDE WORLD TO THE INSIDE WORLD (HIS HOME)... HE OPENED THE RED DOOR; HE OPENED THE RED DOOR