Quietly as a shadow the little Frenchman crept from one of the wide, shutterless front windows to the other, looking intently into the darkened interior of the house, then, with upraised finger warning us to caution, he tiptoed from the porch and began making a circuit of the house, pausing to peer through each window as he passed it.

At the rear of the cottage was a one-story addition which evidently housed the kitchen, and here the blinds were tightly drawn, though beneath their lower edges there crept a faint, narrow band of lamplight.

“Ah—bien!” the Frenchman breathed, flattening his aquiline nose against the windowpane as though he would look through the shrouding curtain by virtue of the very intensity of his gaze.

A moment we stood there in the darkness, de Grandin’s little waxed mustache twitching at the ends like the whiskers of an alert tomcat, Gervaise and I in total bewilderment, when the Frenchman’s next move filled us with mingled astonishment and alarm. Reaching into an inner pocket, he produced a small, diamond-set glasscutter, moistened it with the tip of his tongue and applied it to the window, drawing it slowly downward, then horizontally, then upward again to meet the commencement of the first downstroke, thus describing an equilateral triangle on the pane. Before the cutter’s circuit was entirely completed, he drew what appeared to be a square of thick paper from another pocket, hastily tore it apart and placed it face downward against the glass. It was only when the operation was complete that I realized how it was accomplished. The “plaster” he applied to the window was nothing more nor less than a square of flypaper, and its sticky surface prevented any telltale tinkle from sounding as he finished cutting the triangle from the windowpane and carefully lifted it out by means of the gummed paper.

Once he had completed his opening, he drew forth a small, sharp-bladed penknife, and working very deliberately, lest the slightest sound betray him proceeded to slit a peephole through the opaque window-blind.

For a moment he stood there, gazing through his spyhole, the expression on his narrow face changing from one of concentrated interest to almost incredulous horror, finally to fierce, implacable rage.

“À moi, Trowbridge, à moi, Gervaise!” he shouted in a voice which was almost a shriek as he thrust his shoulder unceremoniously against the pane, bursting it into a dozen pieces, and leaped into the lighted room beyond.

I scrambled after him as best I could, and the astounded superintendent followed me, mouthing mild protests against our burglarious entry of Mrs. Martin’s house.

One glance at the scene before me took all thought of our trespass from my mind.