midnight
`` I do n't think she 'll dare -- but she might . She 's only a pawn , but a pawn can cause a lot of trouble at times -- a pawn may become a queen and give the mate . When a pawn threatens trouble it 's best to -- remove it . '' He went out and came back a little late and busied himself with a four-move chess problem which absorbed all his attention , and which he did not solve to his satisfaction till past midnight . Then he went upstairs to bed , but at the door of his room he paused and went on very softly up the narrow stairs that led to the attics above . Outside the one in which Dunn slept , he waited a little till the unbroken sound of regular breathing from within assured him that the occupant slept . Cautiously and carefully he crept on , and entered the one adjoining , where he turned the light of the electric flashlight he carried on a large , empty packing-case that stood in one corner .