The lower room of the lighthouse bore all the evidences of a typical bomb manufactory. The odor of chemicals hung heavy in the air. Tables were loaded with retorts and measuring glasses. Lengths of leaden pipe and great jars of acid were stored on broad shelves. Grant marvelled at the great stores of material on hand, and the indications of preparations being made for wholesale destruction. In one corner of the room were several packing boxes labelled "Dynamite," and coiled lengths of fusing. Grant, hands in pocket, had taken a mental inventory of the contents of the room. It would be necessary to secure further help. The lighthouse must be guarded until the destructive store of materials it held could be removed to places in which they could put them to better use. He walked musingly to the window. Far down the inlet the crowds of skaters still held away and the late afternoon sun shone brilliantly on the myriad colored throng. It was very quiet in the room. So quiet indeed that Grant started suddenly at a muffled but clearly audible "Click!" The sound was a familiar one. It was the click of the hammer of a gun that had failed to fire, and it came from above. For one moment Grant hesitated as a succession of thoughts passed through his brain. Leading to an upper room at one corner was a ladder. His assistant, whoever he was, was in that upper room! Grant made a dash for the ladder--but his onrush was stopped midway as a revolver, thrown with heavy force, caught him above the eye and hurled his body back to the floor, unconscious. A moment later, with a scurry of footsteps, a man rushed down the ladder. He paused to glance at the body and around the room. An end of fusing lay near at hand. With a quick movement he jerked it out and whipping a match from his pocket lighted the end. The other end lay across a box of dynamite--and the unconscious body of Grant lay on the floor. With a grunt of satisfaction, as the red flame caught at the fuse and then died down to a glowing, growing ember that slowly but obstinately ate its way along the fuse, the spy opened the door and was gone. An automobile was approaching, its course marked by clouds of snow. In the machine was the man to whom Dixie Mason had signalled her message of distress, and with him two others.