"I am so curious.

How do you suppose they worked this trap from here?
They did not press the spring in the molding." He pointed to one side of the opening, where part of the supporting mechanism was now visible.
"They worked that.

It is all simple enough on this side of the trap; the puzzle is about the other.

How did they manage to have all this mechanism put in without rousing any one's attention?
And why so much trouble ?" "Some time I will tell you," I replied, putting my foot on the step.
"O girls!" I exclaimed, as two screams rang out above and two agitated faces peered down upon us.

"I've had an accident and a great adventure, but I've solved the mystery of the ghost.