At last, something like dim veils of whiteness began to draw and shimmer on the eastern skyline—­the vague glare of the sun-crisped Sahara flinging its furnace ardor to the sky.  To catch first sight of land, the Master and Bohannan climbed the ladder again, to the take-off, and thence made their way into the starboard observation gallery.  There they brought glasses to bear.  Though nothing definite could yet be seen through the shrouding dazzle that swaddled the world’s rim, this fore-hint of land confirmed their reckonings of latitude and longitude.

“We can’t be more than a hundred and fifty miles west of the Canaries,” judged the major.  “Sure, we can eat supper tonight in an oasis, if we’re so minded—­with Ouled Nails and houris to hand round the palm-wine and—­”

“You forget, my dear fellow,” the Master interrupted, “that the first man who goes carousing with wine or women, dies before a firing-squad.  That’s not the kind of show we’re running!”

“Ah, sure, I did forget!” admitted the Celt.  “Well, well, a look at a camel and a palm tree could do no harm.  And it won’t be long, at this rate, before—­”

A sudden, violent concussion, far aft, sent a quivering shudder through the whole fabric of the giant liner.  Came a swift burst of flame; black, greasy smoke gushed from the stern, trailing on the high, cold air.  Long fire-tongues, banners of incandescence, flailed away, roaring into space.

Shouts burst, muffled, from below.  A bell jangled madly.  The crackle of pistol-fire punched dully through the rushing swiftness.

With a curse the major whirled.  Frowning, the Master turned and peered. Nissr, staggering, tilted her beak sharply oceanward.  At a sick angle, she slid, reeling, toward the burnished, watery floor that seemed surging up to meet her.

A hoarse shout from the far end of the take-off drew the Master’s eyes thither.  With strange agility, almost apelike in its prehensile power, a human figure came clambering up over the outer works, clutching at stays, wires, struts.

Other shouts echoed thinly in the rarefied, high air.  The climber laughed with savage mockery.

“I’ve done for you!” he howled exultantly.  “Fuel-tanks afire—­you’ll all go to Hell blazing when they explode!  But first—­I’ll get the boss pirate of the outfit—­”

Swiftly the clutching figure scrabbled in over the rail, dropped to the metal plates of the take-off—­now slanting steeply down and forward—­and broke into a staggering run directly toward the gallery where stood Bohannan and the Master.

At the little ladder-housing sounded a warning shout.  The head and shoulders of Captain Alden became visible there.  In Alden’s right hand glinted a service-revolver.

But already the attacker—­the stowaway—­had snatched a pistol from his belt.  And, as he plunged at full drive down the take-off platform, he thrust the pistol forward.