Read it through once

With an admonitory gesture to keep them back, he stooped, and looked in through the crevice in the wall. Soon raising his head again, he struck twice or thrice upon the door--evidently with no other object than to make a noise there. With the same intention, he drew the key across it, three or four times, before he put it clumsily into the lock, and turned it as heavily as he could.