McIver had unscrewed the deadbolt on the back door. He got a screwdriver as a rebate from Lowe's b/c of the gift certificate we bought for GranDaddy before Christmas. This would be why he was quiet in the living room - NOT because he was sitting and quietly reading books to himself.
Olivia was happy to point out the obvious - "We can't go outside because the lock is missing." Which explains the dragging of the stool so he could go out the front door (he can't undo the lock on the laundry room door).
Now we have a new made-from-scratch playset. (The tape measure came in today's mail - another freebie, although, I thought we only ordered the screwdriver.)