"In turn, I hope my hunch is also correct," Illya said.

"It has a good chance. If what you tell me of your theory is true, the exact location of the Murchison-Spears box is critical—which is why we're lucky that T.C.A. equips its Tridents with a baggage compartment as far back as this."

"Yes, our duplicate box is as far away from the one in the cockpit as possible. I suppose that's why you made such a point of mentioning that we would be up front with the pilots—to tempt them to concentrate on that end of the plane."

"Sure. I figure that, since they know we're aboard and we know something of the system at least, then they're bound to try to bring the plane down. But it's a terrible risk, in a way—the crew's lives are at stake as well as our own."

"But we did manage to get all the passengers transferred to a relief flight ten minutes later, Napoleon."

"True. Nevertheless I—Wait a minute! The intercom's coming on!"

Over the noise of the jets, a metallic, disembodied voice was speaking: "Hello, hello. Third pilot here. We are just passing Frejus and the M-S gear is in action. Are you ready to start operating? Are you ready to start operating? ..."

"Solo to Third Pilot," Napoleon Solo said crisply above the racket of the jets. "We are ready to start....And just for the record, here's a recap on the M.O. You have the airplane's normal M-S box in your cabin, receiving signals from Nice and the ground, and the box interprets them and adjusts the plane's controls in such a way as to effect a correct landing. We have a duplicate M-S box back here, receiving the same signals but not hitched up in any way to the controls. The aim of the operation is to check the readings of the two boxes one against the other—and spot any discrepancies if present: okay?"

"Roger. Our box up here has dials indicating distance from touchdown in meters, glide angle, and height in meters. I am to read you the relevant figures from our dials at quarter minute intervals, and you will write these down and check against your own readings at the same time."

"Roger. You can start any time you like."

"Wilco. First reading coming up in fifteen seconds."

Solo picked up the board with its prepared paper and poised a ballpoint over its surface as Illlya Kuryakin threw a switch and studied the needles trembling across the dials in the suitcase. In the dim lighting of the baggage compartment his bland face, normally so placid, appeared strained and anxious.

"First reading," the clipped voice on the intercom was saying: "Distance seventeen thousand five hundred; glide angle five per cent; height five thousand and forty."

"Seventeen thousand five hundred; five per cent; five thousand and forty," Solo repeated, writing the figures on the chart as Illya bent over the dials.

"Check," the Russian called. "One seven five double-o; five; five-o four-o."

Solo wrote the second set of figures below the first.

"Second reading: fourteen six fifty; five per cent; four thousand six hundred."

Solo repeated the figures, wrote them down and looked across at Illya.

"Check," Kuryakin called again. "One four six five-o; five; four six double-o."

"Third reading: twelve thousand; eleven per cent; four thousand and fifty."

"Check. One two o double-o; eleven; four-o five-o..."

Through the small double window on the port side of the baggage compartment, isolated lights spangled the dark bulk of the Alpine foothills massing against the sky to the north. Something on one of the luggage racks squeaked protestingly as the Trident's angle of descent steepened. Over the clamor of the engines, now altering in pitch, a faint rumble followed by two distant thumps marked the lowering of the wheels.

"... Fifth reading: six thousand and twenty; fifteen per cent; one thousand six hundred."

"Check."

The lights of the coastal strip streamed past the port window, long chains of street lamps, illuminated hotels and automobile headlights whirling past them into the darkness as the great plane forged inexorably onwards towards the invisible runway. Through the starboard porthole, a lighthouse far out to sea winked twice against the dark.

"Sixth reading: three thousand two hundred; eleven point five per cent; eight hundred and fifty."

"Check. Three two double-o; eleven point five—No! Wait, wait...the altitude reading's different! Napoleon—look!"

Solo was beside the dials in a flash. The needle of the height indicator was sinking steadily from 830 to 820.

The equipment in the cockpit, which was directing the plane's controls for landing, was registering the ground as between twenty and thirty meters lower than it actually was.

"Seventh reading: eight hundred and fifty; seven per cent; two hundred and ten."

The needle on the altimeter trembled past the 170 mark.

In seconds the pointer would be at zero—while that on the gear controlling the aircraft would still show between 40 and 50...

"Emergency!" Solo shouted into the intercom. "Emergency! For God's sake take over on manual and overshoot—your altimeter reading's gone all to hell!"

"Wilco." A different voice spoke coolly from the amplifier. "Second pilot speaking. Hold on—I am going to overshoot."

The thunder of the jets rose to a shrill scream; the Trident lurched forwards and up under the surge of power. Illya saw trees, airport buildings, parking lots, a Boeing 707 being refueled on the airport apron, whisk past and down, and then they were away and climbing over the glittering crescent of the Baie des Anges with the twin ribbon of the Promenade des Anglais dwindling beneath them.

"... and tell your Navigator for God's sake to get a fix on the position where the readings began to differ—the sixth, I think it was," Solo was calling as the Trident banked seawards in a steep climbing turn and headed back for its second approach.

A few minutes later they made a perfect touchdown under manual control and taxied slowly back to the apron.

Matheson and the airport director met them in a jeep. "I thought we'd be going back with two empty seats for a moment," Matheson said as they climbed down the portable companionway to the ground. "You were flying straight into the deck like the one last night. Still—Warwick caught her just in time and all's well that ends well, eh? I expect you could do with a drink..."

Solo mopped his brow with a handkerchief. "I guess it was a pretty close shave at that," he admitted. "As for the drink—the answer's yes, please!...Illya's just superintending the unshipping of both sets of Murchison-Spears equipment so that your boys can get to work right away on comparison tests. Now perhaps we'll be able to say just how the deed is done..."

But at midnight, Matheson came up to them in the airport restaurant, where they were sitting over coffee and cognac, and dropped into a vacant chair at their table with an expression of astonishment on his face. "It beats me," he said blankly. "We've really done the most exhaustive tests on both sets of equipment—even had them taken up in a helicopter to check them under operating conditions—and what do you think we found?"

"That both sets were working perfectly—and giving precisely the same readings all along the line," Solo said with a grin.

The Technical Director started, absently catching his empty pipe as it fell from his mouth. "But that's just it!" he exclaimed. "How on earth did you know? What have you chaps found out?"