When takeoff clearance came down from the control tower, Lemk eased the

thrust levers forward and the Boeing 720-B rolled over the damp concrete

and rose into the soggy air.

As soon as he reached his cruising altitude of 10,500 meters and engaged

the autopilot, Lemk unbuckled his belt and rose from his seat.

"A call of nature," he said, heading for the cabin door. His second

officer and engineer, a freckle-faced man with sandy hair, smiled

without turning from the instrument panel. "I'll wait right here."

Lemk forced a short laugh and stepped into the passenger cabin. The

flight attendants were preparing the meal service. The aroma of Beef

Wellington came stronger than ever. He made a gesture and drew the

chief steward aside.

"Can I get you anything, Captain?"

"Just a cup of coffee," replied Lemk. "But don't bother, I can manage."

"No bother." The steward stepped into the pantry and poured a cup.

"There is one other thing.

"sir?"

"The company has asked us to take part in a government sponsored

meteorology study. When we're twenty-eight hundred kilometers out from

London, I'm going to drop down to fifteen-hundred meters for about ten

minutes while we record wind and temperature readings. Then return to

our normal altitude."

"Hard to believe the company went along. I wish my bank account totaled

what it will cost in lost fuel."

"You can bet those cheap bastards in top management will send a bill to

Washington."

"I'll inform the passengers when the time comes so they won't be

alarmed."

"You might also announce that if anyone spots any lights through the

windows, they'll be coming from a fishing fleet."

"I'll see to it."

Lemk's eyes swept the main cabin, pausing for an instant on the sleeping

form of Hala Kamil before moving on. "Did it strike you that security

was unusually heavy?" Lemk asked conversationally.

"Of those reporting told me Scotland Yard caught wind of a plot to

assassinate the Secretary-General."

"They act as though there's a terrorist plot under every rock. I had to

show my identification while they searched my flight bag."

The steward shrugged. "What the hell, it's for our protection as well

as the passengers'."

Lemk motioned down the aisle. "At least none of them looks like a

hijacker."

"Not unless they've taken to wearing three-piece suits."

"Just to be on the safe side, I'll keep the cockpit door locked. Call

me on the intercom only if it's important."

"Will do."

Lemk took a sip of his coffee, set it aside and returned to the cockpit.

The first officer, his copilot, was gazing out the side window at the

lights of Wales to the north, while behind him the engineer was occupied

with computing fuel consumption.

Lemk turned his back to the others and slipped a small case from the

breast pocket of his coat. He opened it and readied a syringe

containing a highly lethal nerve agent called sarin. Then he faced his

crew again and made a fumbling step as if losing his balance and grabbed