They sprinted away from the house. As they crossed the road, they heard the backdoor bolts lock again; they really were on their own. For the first time since the events of the summer, Jack and Itch had no protection, no security, no guardian angels to watch over them. Terrified and exhilarated in equal measure, they flew down the road toward the golf course. They were aware that the cameras outside the house could pick them up at any time, but Itch’s guess was that all Danny’s attention was on events at the academy. As far as he was concerned, the cousins were safely in bed.

They kept low across the deserted golf course—two crouched silhouettes. The distant flashing lights of the emergency vehicles reflected off the low clouds, but Itch and Jack were concentrating on their flat-out, heads-down charge for the beach. They caught their breath by the beach huts, then jumped down the steps onto the sand. Keeping as close to the cliffs as possible, and thankful it was low tide, they scrambled over the rocks toward the canal.

They hadn’t spoken since leaving the house; they were running too fast to chat. But now, standing at the end of the beach by the huge boulders that marked the start of the path up to the canal, they needed to work out what they were doing. They gasped for breath, thrilled by their freedom but also petrified.

“What happens now?” asked Jack eventually, once her breathing had slowed.

Itch shook his head—he still couldn’t speak. He was weaker than he had been before the radiation sickness, and Jack had always been fitter than he was, anyway. “Are there any lights on?” he asked at last.

Jack climbed up on a rock and peered cautiously over the canal. “Don’t think so,” she said. “The whole row looks dark. Actually, wait …” She straightened a little. “Difficult to see properly, but maybe there’s a dim light downstairs. What do you think?” They changed places.

“Could be,” Itch said. “Let’s go closer.”

The path to the canal was a gentle climb to a set of locks. The old waterway carried on inland, with towpaths on either side. A few narrow boats were moored close by, but there were no signs of life; in fact, Itch and Jack hadn’t seen a soul since leaving the house. They walked slowly up the path until the cottages were in full view. Jack was right—there was a soft glow from Watkins’s living room. They ducked down at the top of the path, their line of sight blocked by a barge.

“Could just be a security light, Itch—doesn’t mean there’s anyone there.”

He nodded and set off across the lock gates that crossed the canal. The gentle V-shaped beams took them to the towpath on the other side, where he pointed at the sandy path that led into the dunes. It looped around the six cottages, with small offshoots to each backyard. The total darkness of the first five cottages emphasized the indisputable glow that was coming from the sixth.

Jack and Itch opened the small gate that led to the roofless house next to Mr. Watkins’s. They crouched behind the low fence, close to the wind-eroded brickwork. The big window of their teacher’s living room was a few feet away, curtains drawn. They listened.

Silence.

“Call Mr. Watkins again. Last time,” said Jack, and Itch dialed the number.

“Voicemail. Same as before,” he told her. “Let’s try the kitchen.”

They stepped over the fence and, ducking below the curtained living room window and back door, reached the kitchen window. It was dark and curtainless, and they could see that the kitchen was empty.

“We either go in or go home,” said Jack.

They looked at each other for a moment, each knowing that they weren’t about to give up. Itch stood up and tried the back door.

It was open.

They quickly stepped inside and, heart racing, Itch opened the kitchen door.

The light was coming from a small gas fireplace at the far end of the living room, its flames just adequate to illuminate the figure of their homeroom teacher sitting in the armchair. He was crying.

“Mr. Watkins!” Itch called, but as he ran over, he heard a gasp behind him. Spinning toward the sound, he saw Shivvi’s arms close around Jack’s mouth and chest. She pulled Jack’s head back and held it there.

“Hello, Itch. Hello, Jack. Good timing. Thought you’d be a while yet, but you both moved fast,” said Shivvi. “I’m impressed. We’ve been waiting, John and I. Haven’t we, John?” She reached over and yanked the gag out of Watkins’s mouth.

“I’m so sorry,” he murmured. “So sorry—she broke in, and I … She took my phone. That’s how you got that text.” They saw now that he had been tied to his chair with thick rope around his chest and feet.

Jack coughed and retched, and Shivvi eased her head forward. “You are a pretty thing,” she said. “Let’s hope your cousin’s famed stubbornness doesn’t cause anything to happen to you.” She held Jack’s head back with one hand and lifted the baseball bat with the other.

Itch exclaimed and started toward her. “No! Leave her alone! Please—she’s done nothing, she doesn’t know—”

“Yes, but you do,” said Shivvi, stepping back and pulling Jack’s head back farther. Jack retched again, arms flailing. “It’s very straightforward: you tell me where the rocks are or I’ll break the rest of your sweet cousin’s fingers. One by one.”

Itch and Watkins both cried, “No!”

“And then her toes. And then … who knows?”

“You wouldn’t do that!” said Watkins, shaking again.

“You forget who smashed Lucy Cavendish’s face.”

“So that really was you.”

“Yes, and you should thank me, Itch. That was punishment for what she did to Jack in the hockey match. Not a nice girl. I can’t let just anyone mete out justice, you know. That’s my job.”

“You’re crazy,” said Itch quietly, “and I never knew.”

“Maybe I am crazy,” said Shivvi, “but I have Jack and I have a baseball bat. Are you going to tell me where the 126 is? I don’t have much time, but I can break bones very quickly. You’d be amazed….” She raised the bat.

“Stop! Of course I’ll tell you!” shouted Itch. “Just let her go!”

Shivvi released some of the pressure. “That didn’t take long, did it?” she laughed as Jack gasped for air.

Itch wanted to go and help Jack but the bat pointed at him. “No. Stay.” Shivvi let go of Jack, who fell to her knees, her hands clutching her throat. “Hands on the table, please, Jack, where I can see them.”

“OK, OK,” she croaked as she gently placed both hands on Watkins’s coffee table.

“Good girl.” Shivvi raised the bat above Jack’s fingers. “The address, Itch. Tell me now!”

“OK! All right! The well at the Fitzherbert School! The rocks are down the well! Leave her alone!”

Watkins gasped, and Jack started to cry.

“Where’s that?” shouted Shivvi. “Tell me!”

“Just outside Brighton! Now, let her go.”

Shivvi lowered the baseball bat and Itch went to his stricken cousin.

“You shouldn’t have told her,” Jack sobbed into his ear. “Oh, Itch, what are we going to do now?”

Shivvi ordered Itch to sit down at Watkins’s computer. “Show me,” she said, and he showed her the location and the history of the Woodingdean Well.

That took two minutes, Itch thought. All that struggle, pain, and vomit it took to hide them, and I just told her where they are after two minutes. He kept glancing around at Jack, but she seemed OK. What choice did I have?

“Hands back on the table,” Shivvi ordered, and Jack wearily complied. “Any clever moves from you, Itch, and—”

“Yes, I get it,” he snapped. “I’ve worked out that you’ll do what you say. And that you’re mental. I’m doing what you asked, aren’t I?”

“Print that out,” ordered Shivvi, and Itch clicked on a map of Brighton, and on the cross-section of the well from a local history page.

She studied the information. “Where does the water start?” she asked.

“At the horizontal part, 400 feet down. Then another 885 feet to the bottom. Best of luck with that.”

Shivvi ignored the sarcasm. “You got them all the way down there?” She whistled and said something in Malay that sounded to Itch like a pretty strong swear word.

She noted something down on a pad and checked her calculations on Watkins’s computer. “I guessed they might be in a mine or underwater somewhere, and I’ve prepared for most eventualities I could think of, but I never thought you’d have made it so difficult. I’m impressed, schoolboy, I really am.” Itch said nothing. “Flowerdew said you were an idiot. Like so much he told me, it turned out to be wrong.”

“You’re working with Flowerdew?” said Itch, sickened just to hear his name.

“We met. I killed him.” Shivvi smiled. “Ooh, that sounded good. I’ll say it again. We met. I killed him.”

“You … killed Flowerdew?” Itch was stunned.

“Pushed him off his oil rig,” said Shivvi, enjoying the sight of the three shocked faces. “I know you’re all glad really. Did everyone a favor…. Tell me I’m wrong.” She glared at her prisoners, challenging them.

“Prison would have been fine,” said Jack. “Prison forever maybe—but no one deserves to die like that.”

Shivvi spat. “Pathetic, Jack. You’re even weaker than you look. My only regret is that he didn’t live to see me get hold of his precious 126.”

“Well, you’ll have to be quick,” said Jack.

“And why would that be?”

Jack turned and looked directly at Shivvi. “Because the school has just been sold, that’s why. To a Spanish firm. It’s in Mr. Watkins’s magazine.”

Another string of Malay words, and Shivvi read the article, which was still open on the table.

“OK—we leave now. But first, a few photographs, please!”

From a black duffle bag she produced a long, heavy, carefully wrapped package. She removed the canvas cover slowly, followed by some bubble wrap.

Before half had been peeled away, Itch exclaimed, “Cesium! You do have it!”

“Sure do,” said Shivvi, and she held out the three-foot-long silver and glass tube. It had a red wax seal over a label written in Russian. CCCP was stamped on both ends, and through the glass they could see a large lump of silvery metal submerged in an oily liquid.

“When I hunted around for some elements to impress the schoolboy here, I found some very shady characters. They had some boring stuff, but they also had things like this.” She held it up to catch the light from the fire. “It melts when I hold it—look.” As they watched, the solid silver metal began to change to a liquid gold.

In spite of the danger, Itch found it beautiful. “Melting point 83.19 degrees Fahrenheit,” he said. “Never seen that before.”

Shivvi lowered the tube. “Classic, Itch, really classic. You’d better hope that’s the only cesium reaction you see. They think I’m about to drop it at your school, but that would be a waste.”

Watkins cleared his throat. “What would happen if you dropped it?”

“A big fire, very quickly,” said Itch.

“Correct. And I have a few of them to keep me going.”

Itch looked into the bag and counted at least five other tubes. “Where did you get them?” he asked.

“When you mix with criminals and thieves, it’s really not difficult, you know. You should try it sometime, schoolboy.” Shivvi walked over to where Jack knelt with her hands on the table, cesium in one hand and the baseball bat in the other.

Jack tensed and cowered a little.

“Sit there and take off your jacket,” Shivvi ordered, pointing to a chair.

Gingerly Jack stood up and went over to the upright wooden chair.

“Jacket off. Quickly.”

Puzzled, but in no position to argue, Jack unzipped her jacket and dropped it on the floor.

From the depths of the bag, Shivvi produced a brown vest and threw it over. “Put that on.”

Jack looked at its many pockets and zippers, puzzled. When she had put it on, Itch suddenly realized what they were for. Shivvi stepped in front of her and slotted the cesium tube into one of the deep pockets, and he felt the blood drain from his face.

Mr. Watkins understood it too. “Dear God …”

“I know,” said Shivvi. “It is good, isn’t it? I got the vest from one of those clothes shops for old people.” She reached for the thick elastic band on the breast pocket and snapped it over the top of the cesium tube, then grabbed some rope. “Tie her to the chair.”

“Like hell I will,” said Itch. He used one of his dad’s “oil-rig phrases,” and Shivvi laughed.

“Except that when it comes to saving your cousin, you’ve already shown me you’ll do anything. So save your big talk for when you need it. Tie her up.” She brandished the bat, and Itch did as he was told.

“Sorry,” he whispered as he passed the rope around the chair, Jack’s chest and the cesium. He kept it loose, but Shivvi didn’t seem to mind.

“Step away,” she said, and produced a phone. Taking pictures of the terrified Jack, she said, “These will come in useful. Cornwall’s first suicide bomber! Might not make your parents’ mantelpiece, but you never know who might need to see them.” Turning to Watkins, she added, “And if the police turn up, if I even hear a siren, Itch and Jack die. Understand? You tell anyone where we are heading and you’ll be saying good-bye to these brave, stupid children. Got that?”

Watkins nodded.

“You’re worse than Flowerdew,” said Itch.

“Thank you—I hope so,” Shivvi said. “Now, schoolboy—untie her.”

Itch did so, and Jack shakily got to her feet.

“Jack, you stay with me. You walk ahead, schoolboy. If you do anything stupid—”

“Shut up, Shivvi. I get it, OK? I told you, I get it.”

“And one more thing. Empty your backpack. Now.”

Itch hesitated briefly, then undid the straps and tipped tubes, packets, and containers onto the floor; a small glass vial broke as a piece of iron rolled on it.

“Anything nasty?” asked Shivvi.

“Helium. Just helium,” said Itch.

Shivvi laughed and picked up the baseball bat. “Time to go.” She turned to Watkins. “I’m sure you wouldn’t want to say anything, sir, but I’m afraid I can’t take that risk.”

She swung the bat. It hit Watkins just above his left ear.