Breathing heavily, Samuel leaned back against the sink.

“I’m never using that toilet again,” he said to Boswell, but Boswell was no longer at the door. Instead, he had returned to the window, where Samuel now joined him. Together they watched as the streetlight across from the house came on once more, and the next one extinguished itself, and so on until at last the corner was plunged into darkness for a moment, and something fled away into Stoker Lane.

Before it disappeared, Samuel and Boswell caught a glimpse of it.

It looked like a woman.

In fact, it looked very much like Mrs. Abernathy.

SAMUEL DIDN’T SAY MUCH at breakfast the next morning. His mother noticed how subdued her son was.

“Is everything all right, dear?” she asked.

Samuel just nodded, and ate his cornflakes. He wanted to tell his mother what had happened the night before with the pool of Darkness, but he couldn’t. She wouldn’t believe him, and he had no proof. He had no idea where the Darkness had ended up, and was at first a little worried that it might be stuck in one of the household pipes, waiting for a chance to emerge. Once he had thought about it for a while, though, he realized that it was probably lost in a smelly old sewer, which was just fine by Samuel. Still, he had taken the precaution of gluing the toilet seat closed using superstrong adhesive. He was the only one who ever used the little bathroom anyway, and as long as he was careful nobody would discover for a while what he had done.

But Samuel was also very frightened, for his mother and for himself. He remembered Mrs. Abernathy’s threat to kill his mother if he continued to try to convince her of what he knew. The demon under the bed had been bad enough, but at least that could be reasoned with. The Darkness had been something else entirely. He had been lucky last night; Boswell’s bravery had saved him, but Boswell might not be able to save him, or his mum, from whatever came next.

Because Samuel was sure of one thing: Mrs. Abernathy wasn’t going to give up. The Darkness had simply been her latest attempt to silence Samuel. Others would follow, and eventually she would succeed.

Samuel didn’t want to die. He quite liked being alive. But as he tried to come to terms with how scared he was, he began to feel angry. Mrs. Abernathy was evil. She wanted to do something awful, so awful that the world would never be the same after it, if there was even any world left once the gates were opened. She had to be stopped, and Samuel was determined to fight her until his last breath.

It was at that moment that fortune began to turn in Samuel’s favor.

There was a small portable television in the corner of the kitchen. Samuel’s mother sometimes liked to watch it while she was having breakfast. The volume was turned down low, and the news was on. Samuel glanced up and saw a man in a white coat talking. Behind him was what looked like an enormous series of pipelines. Samuel knew what it was: the Large Hadron Collider in Switzerland. He had watched a documentary about it earlier in the year and, although he hadn’t understood everything that had been discussed, he thought it all sounded like fascinating stuff. He reached for the remote control and turned up the volume.

The scientist, whose name was Professor Stefan, looked a bit embarrassed. It became clear that he was trying to explain why the collider had been shut down. Samuel knew the collider hadn’t worked properly the first time it was turned on, and the scientists had been forced to tinker with it for a while before it began running to their satisfaction. Now, after all the money that had been spent on it, it still didn’t appear to be working the way that it should.

“Well,” said Professor Stefan, when the reporter pointed this fact out to him, “that’s not entirely true. It was working perfectly, but then there was an, um, unanticipated release of unknown energy.”

“What does that mean, exactly?” asked the reporter.

“Well, to put it in layman’s terms, a bit flew off, and now we’re trying to find out what it was.”

“A bit?” said the reporter.

“A particle of energy,” said Professor Stefan, “but one that has not been encountered before, and appears to show unusual characteristics.”

“What kind of characteristics?” said the reporter.

“Well, the collider is a vacuum, and therefore it’s sealed. It simply should not be possible for anything to find its way out of there.”

“But now you think that something has?”

“We believe so. It may just be a leak, so we’re checking every inch of the collider for possible breaches. As you can imagine, that’s a time-consuming procedure. In the meantime, we’re going back over our systems in an effort to determine precisely what we’re dealing with.”

The reporter thought over what he had just been told.

“Is there any possibility that this ‘energy’ might be dangerous?”

“Oh, none whatsoever,” said Professor Stefan.

Samuel thought that he seemed very sure of this for someone who didn’t know what exactly the energy was.

“And when precisely did you become aware of this energy leak?” asked the reporter.

“At precisely seven thirty P.M. on October twenty-eighth,” said Professor Stefan. “The collider was shut down shortly afterward.”

Samuel paused, a spoonful of cornflakes suspended between the bowl and his mouth. Seven thirty P.M. on October 28. At seven thirty P.M. on October 28 Samuel and Boswell had been sitting on the Abernathys’ wall when they’d heard the bang from the Abernathys’ basement, when they’d seen the blue light and smelled that nasty smell. It might be a coincidence, of course, but for the first time Samuel sensed that there could be someone out there who might be prepared to listen to him.

Samuel sat before his computer and examined the website for CERN. He couldn’t find a telephone number, but there was a section entitled “Ask an Expert.” Samuel didn’t know how long an expert might take to answer his question, or even if what he had to say counted as a question at all. He thought hard, then composed his message to CERN:

Dear CERN,

My name is Samuel Johnson, and I am eleven years old. I have reason to believe that I may have found your missing energy particle, or know where it ended up. I think it is in the basement of number 666, Crowley Road, in the town of Biddlecombe, England. It is owned by a couple named the Abernathys. It is very blue, and smells of rotten eggs. The energy, that is, not Biddlecombe. It materialized there at precisely seven thirty P.M. on October 28. I enclose a drawing of what I saw in the basement, scanned into the computer for your information.

Yours sincerely,

Samuel Johnson

P.S. I believe Mr. and Mrs. Abernathy have become possessed by demons, and may be using the energy to open the gates of Hell.

When he was finished, Samuel checked his spelling and went over the letter once again to make sure that he had included all the important details. He had considered leaving out the bit about Hell, but thought it might add a sense of urgency to his message. After all, he didn’t know how many people wrote to “Ask an Expert” every day, or if there was just one expert answering the questions or a whole team. In any case, he thought it was important to attract CERN’s attention and, if nothing else, the mention of demons and Hell was likely to make his message stand out.

He pressed Send, and his missive shot off into cyberspace. He considered staying at his computer and waiting for a reply, but he suspected that, even if someone read his message promptly, a certain amount of discussion would still be required before it was answered.

Samuel was not about to sit around doing nothing. It was Halloween, and he had heard Mrs. Abernathy say that she and her fellow demons had four days to prepare the way. Samuel didn’t know precisely what “preparing the way” meant, but by any calculation four days from October 28 led to November 1. He had a terrible feeling that, at some time the next day, the gates of Hell would begin to open.