The Fallable Fiend by L. Sprague deCamp

platform whereon it looked, a narrow, spiral stair continued up around the tower for one complete turn, ending at a higher and smaller door.
    The castellated upper rim of the tower was higher yet. The booms of catapults projected out over the edge. The roof also upheld a complicated structure, which I saw from afar but did not understand until I had followed Noïthen through the main portal, past a pair of tall, blond guards.
    “Who are those fellows?” I asked Noïthen. “They look not like Novarians.”
    “Mercenaries from Shven. We are no warmongers, but a nation of peaceful farmers and merchants. Hence we hire the Shvenites to do our bloodletting for us. In peacetime, as now, they serve as our civic guard and police.”
    Inside the portal, a spacious circular courtyard, open to the sky, filled the center of the tower. Around the walls, a series of huge casemates, upheld by arcades, provided space for the city’s defenders and their equipment. Above the topmost of these rows of chambers rose the ring-shaped roof whereon stood the catapults.
    There also arose the structure I had seen from without. It was a huge mirror on a clockwork mounting, so that it followed the course of the sun during the day. In planning his city, Ardyman had slighted the problem of ventilation. To see in their burrows, the Irians had to burn lamps and candles, and to cook they had to burn fuel. The smoke and soot of these fires distressed them, to say nothing of the vitiation of the air. Furthermore, this condition worsened as the city grew and its galleries extended farther and farther into Mount Ir.
    At last, an ingenious syndic persuaded the people to install a system of lighting by reflected sunlight. This at least made lamps superfluous on sunny days. The main mirror, mounted atop Ardyman’s Tower, cast the sun’s beams down into the courtyard, whence another mirror reflected them down the main street—Ardyman Avenue—of Ir. Smaller mirrors diverted the rays down side streets and thence into individual dwellings.
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    When I speak of cave dwellings, do not envisage a natural cavern, bedight with stalactites and inhabited by a handful of skin-clad primitives. Ir City had been hewn from the rock by the ablest Novarian masons. Its aspect, save for the roof of rock overhead in place of sky, was not unlike that of any rich city of the Prime Plane.
    The house fronts, which reached up to this stone roof, were like other house fronts. The masons had even carved lines on them to simulate the joints between the bricks or stones of ordinary houses. Since the structure was one solid mass of rock, these carvings served no useful purpose save to make the scene look more familiar.
    Most of the dwellings of Ir were on the same level as the courtyard of Ardyman’s Tower. There were other levels, above and below the main one, but these had been built after the original. As we wound our way along Ardyman Avenue, through the passing throngs, Noïthen asked: “Were you not once indentured to Maldivius the diviner?”
    “Aye, sir. He evoked me from my own plane and later sold my contract to Bagardo the showman.”
    “Did Maldivius suffer some grave loss whilst you were with him?”
    “That he did, sir. A thief made off with his scrying stone, which he called the Sibylline Sapphire. He blamed me for the loss; hence the change in my indenture.”
    “Who took the stone?”
    “It was—let me think—Maldivius said the thief was one Farimes, whom he had known erewhile. Why, sir?”
    “You’ll find out when you know your new mistress, Madam Roska sar-Blixens.”
    “Master Noïthen, have the goodness to explain your system of names and titles. I am but a poor, ignorant demon—”
    “She’s the widow of the Syndic Blixens, and now she’s fain to become a Syndic on her own.”
    We turned into a sidestreet and stopped before one of the larger edifices. We were admitted by a servant: a small, swarthy, hook-nosed man in the robe and head cloth of