[header] How to take out a mortise lock [title] Open the door. [step] On the edge of the door you should see a long brass plate with a latch, a bolt and a couple of buttons. On the inside there is usually a knob that actuates the latch, and a thumb-turn that throws the bolt. 
On the outside, there is usually a grip handle with a small thumb actuated lever, and above this is a lock cylinder and escutcheon. [title] Look carefully at the shank of the inside knob.