The small office in which Woodhouse was installed was situated at the very top of the tower--a room glassed on four sides like the lantern room of a lighthouse, and provided with telescope, a telephone switchboard, range finders, and all the complicated machinery of gunfire control. On one side were trestle boards supporting charts of the ranges--figured areas representing every square yard of water from the nearer harbor below out to the farthest reaching distance of the monster disappearing guns. A second graphic sheet showed the harbor and anchorages and the entrance to the straits; this map was thickly spotted with little, red, numbered dots--the mines. Sown like a turnip field with these deadly capsules of destruction were all the waters thereabouts; their delicate tendrils led under water and through conduits in the Rock up to this slender spire called the signal tower. As he climbed the winding stairway to his newly assigned post, Woodhouse had seen painted on a small wooden door just below the room he was to occupy the single white letter "D." Room D--where the switches were, where a single sweep of the hand could loose all the hidden death out there in the crowded harbor--it lay directly below his feet. Captain Woodhouse's duties were not arduous. He had as single companion a sergeant of the signal service, whose post was at the window overlooking the harbor. The sergeant read the semaphore message from the slender signal arm on the flagship's bridge--directions for the coal barges' movements, businesslike orders to be transmitted to the quartermaster in charge of the naval stores ashore, and such humdrum of routine. These Woodhouse recorded and forwarded to their various destinations over the telephone. He had much time for thought--and much to think about. Yesterday's scene in the library of Government House--his grilling by the two suspicious men, when a false answer on his part would have been the first step toward a firing squad. Yes, and what had followed between himself and the little American--the girl who had protected and aided him--ah, the pain of that trial was hardly less poignant than had been the terror of the one preceding it. She had asked him to prove to her that he was not what she thought him. Before another day was past she would be out of his life and would depart, believing--yes, convinced--that the task he had set himself to do was a dishonorable one. She could not know that the soldiers of the Hidden Army have claim to heroism no less than they who join battle under the sun. But he was to see Jane Gerson once more; Woodhouse caught at this circumstance as something precious. To-night at Government House Lady Crandall's dinner to the refugee Americans on the eve of their departure would offer a last opportunity. How could he turn it to the desire of his heart?