nd a half to three miles wide and of undeterminable length and
depth, had merely been formed by strong, cunning hands into walls,
battlements, houses, mosques, and minarets.

It had been carved out _in situ_, the soft metal being fashioned with
elaborate skill and long patience. Jannati Shahr seemed, on a larger
scale and a vastly more magnificent plan, something like the hidden
rock-city of Petra in the mountains of Edom--a city wholly carved by
the Edomites out of the solid granite, without a single stone having
been laid in mortar.

Wonderful beyond all words as the early afternoon sun gleamed from
its broad-flung golden terraces and mighty walls--whereon uncounted
thousands of white figures had massed themselves--the "Very Heavenly
City" widened to the Legionaries' gaze.

On, up the last slope of the grassy plain the rushing horsemen bore.
Into a broad, paved way they thundered, and so up, on, toward the
great gate of virgin gold now waiting to receive them.

CHAPTER XL

INTO THE TREASURE-CITADEL

Well might those Legionaries who had been left behind to protect Nissr
and the sacred gifts have envied the more fortunate ones now sweeping
into Jannati Shahr. The rear guard, however, formed no less essential
a part of the undertaking than the main body of the Legion.

This rear guard consisted of Grison, Menendez, Prisrend, Frazier,
and Manderson. Their orders were as follows: If the main body did not
return by midnight, or if sounds of firing were heard from the city,
or again if they received direct orders via the Master's pocket
wireless, they were at once to load the machine-guns on board the
liner. They were to carry Myzab on board, also, and with the wireless
spark detonate the explosive which would reduce the Black Stone to
dust.

This accomplished, they were to start the engines and, if possible,
make a getaway--which might be feasible for five men. If they
succeeded, they were to wheel over the city and drop the second
kappa-bomb, also all the remaining explosive, by way of punitive
measures. Well-placed hits might wipe out most of the city and, with
it, the population which had broken the Oath of the Salt.

The main body of the Legion would, of course, also perish in this
_debacle_ if still alive; but the probability existed that before
Nissr could take the air, all would be dead.

The program was explicit. All five men of the rear guard fully
understood its every detail and all had sworn