Ice Station

'Jesus, are you OK,' he said. 'Your mother...'

'She wasn't my mother,' Kirsty said quietly.

'Would it be all right if we talked about this later?' Schofield asked. 'In about twenty-two minutes this place is gonna be water vapor.'

Kirsty nodded.

'Mr. Renshaw,' Schofield said, looking at the shuddering walls all around him. 'What's happening?'

Renshaw said, 'I don't know?'

At that moment, the whole tunnel lurched suddenly and dropped about ten inches.

'It feels like the ice shelf has been dislodged from the mainland,' Renshaw said. 'It's becoming an iceberg.'

'An iceberg ...,' Schofield said, his mind turning. All of a sudden, his head snapped up and he looked at Renshaw. 'Are those elephant seals still out in that cave?'

Renshaw looked out through the fissure.

'No,' Renshaw said. 'They're gone.'

Schofield crossed the tunnel and picked up Gant in his arms, carried her toward the fissure. 'I thought that might happen,' he said. 'I killed the bull. They're probably out looking for him, now.'

'How are we going to get out of here?' Renshaw said.

Schofield hoisted Gant up into the fissure and pushed her through. Then he turned to face Renshaw, his eyes gleaming.

'We're gonna fly out of here.'

The big black fighter stood magnificently in the middle of the underground cavern?its sharply pointed nose tilted downward and its sleek black wings swept low. Large chunks of ice rained down from the cavern's high ceiling and exploded against its fuselage.

Schofield and the others raced across the shaking floor of the cavern and took shelter underneath the belly of the big black plane.

As Schofield held her in his arms, Gant showed him the keypad and the entry-code screen.

The entry-code screen glowed green.

24157817 :_________________________

ENTER AUTHORIZED ENTRY CODE

'Did anybody figure out the code?' Schofield said.

'Hensleigh was working on it, but I don't think she ever figured it out.'

'So we don't know the code,' Schofield said.

'No, we don't,' Gant said.

'Great.'

At that moment, Kirsty stepped up alongside Schofield and peered at the screen.

'Hey,' she said, 'Fibonacci number.'

'What?' Schofield and Gant said at the same time.

Kirsty shrugged self-consciously. 'Two-four-one-five-seven-eight-one-seven. It's a Fibonacci number.'

'What's a Fibonacci number?' Schofield said.

'Fibonacci numbers are a kind of number sequence,' Kir-sty said. 'It's a sequence where each number is the sum of the two numbers before it.' She saw the amazed looks around her. 'My dad showed it to me. Does anybody have a pen and a piece of paper?'

Gant had the diary she had found earlier in her pocket. Renshaw had a pen. At first it dribbled with ink- colored water, but then it worked. Kirsty began to scribble some numbers in the diary.

She said, 'The sequence goes like this: 0, 1, 1, 2, 3, 5, 8, 13, and so on. You just add the first two numbers to get the third. Then you add the second and the third to get the fourth. If you just give me a minute ...,' Kirsty said as she began to scribble frantically.

Schofield looked at his watch.

10:40 p.m.

Twenty minutes to go.

As Kirsty scribbled in the diary, Renshaw said to Schofield, 'Lieutenant, exactly how do you plan to fly out of here?'

'Through there,' Schofield said absently, pointing at the pool of water over on the other side of the cavern.

'What?' Renshaw said, but Schofield wasn't listening. He was busy looking down at the diary as Kirsty wrote in it.

After two minutes, she had three rows of numbers written out. Schofield wondered how long this was going to take. He looked at the numbers as she wrote them:

0,1,1, 2, 3, 5, 8,13, 21, 34, 55, 89,144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10,946, 17,711, 28,657, 46,368, 75,025, 121,393, 196,418, 317,811, 514,229, 832,040, 1,346,269, 3,524,578, 5,702,887, 9,227,465, 14,930,352, 24,157,817

 'And see that,' Kirsty said. 'There's your number. 24157817.'

'Holy shit,' Schofield said. 'OK, then. What are the next two numbers in the sequence.'

Kirsty scribbled some more.

39,088,169, 63,245,986

'That's them,' Kirsty said, showing the diary to Schofield.

Schofield took it and looked at it. Sixteen digits. Sixteen blank spaces to fill. Amazing. He punched the keys on the keypad.

The screen beeped.

24157817 3908816963245986

ENTRY CODE ACCEPTED. OPENING SILHOUETTE

There came an ominous droning sound from within the big black ship and then suddenly Schofield saw a narrow flight of steps fold down slowly from the ship's black underbelly.

He gave Kirsty a kiss on the forehead. 'I never thought math would save my life. Come on.'

And with that, Schofield and the others entered the big black ship.

They came into a missile bay of some sort. Schofield saw six missiles locked into place on two triangular racks, three missiles per rack.

He carried Gant across the missile bay and lay her on the floor just as Renshaw and Kirsty stepped up into the belly of the plane. Wendy hopped clumsily up the steps behind them. Once the little seal was safely inside, Renshaw pulled the stairs up behind her.

Schofield headed forward, into the cockpit. 'Talk to me, Gant!'

Gant called forward, the pain evident in her voice: 'They called it the Silhouette. It's got some kind of stealth feature that we couldn't figure out. Something to do with the plutonium.'

Schofield stepped into the cockpit.

'Whoa.'

 The cockpit looked amazing?futuristic, especially for a plane that was built in 1979. There were two seats: one forward and to the right, the other?the radar operator/gunner's chair?behind it and to the left. The steepness of the cockpit?it pointed sharply downward?meant that the pilot in the front seat sat well below the gunner in the backseat.

He jumped into the pilot's seat just as?bang!?a large chunk of ice exploded against