Devil's Dice by William le Queux

At first I dared not look the exigency in the face. For fully an hour I paced the room in nervous agitation, but the imperative necessity of recovering the box impressed itself every moment more deeply upon me. The crime was, as yet, still undiscovered; therefore, might I not enter, search, find the piece of evidence that would link me with the terrible tragedy, and return in the same manner as on the previous night? Undoubtedly the body was lying silent and ghastly where I left it, and if only I could get in and out of the flat unobserved, I should be free to assist the wretched man who was my friend, and who had held in his possession the extraordinary letter from Sybil.

The mantel-clock told me it was nearly three. At that hour there would be little likelihood of meeting anyone on the staircases, therefore I decided to go.