|"Are you willing to do some more reading?"|
"It's Vim, a creamy white cleanser," I said. "I used it to remove the much heavier residue left by the Comet, and I didn't rinse off all the Vim."
"If nothing else," said Holmes, "you have shown that the powder Slate described could have been left in the Alderney Street flat in quite the same way. As for the question of what the cleaning was intended to hide, we may never know the answer."
"Fingerprints, perhaps?" I suggested.
"It could very well be so," replied the detective. "We must be careful in drawing inferences from flimsy evidence, but we are probably safe to assume that whoever killed Gareth Williams wasn't wearing gloves at the time."
"It seems a minor point," I said.
"And so it may be," agreed my companion, "yet it could turn out to be a significant detail.
"I am prepared to call the counter top experiment a success," Holmes continued. "You may keep it going if you wish, but there is no need to do so."
"I imagine we could have obtained the same information through a short conversation with Mrs. Hudson," I suggested. "Surely she has plenty of experience with cleaning products."
"I much prefer for us to see the results ourselves," replied Holmes. "We've had enough second-hand evidence in this case already."
I could hardly disagree.
"What else have you been doing?" asked Holmes. "Have you done very much reading in my absence?" Thus began a conversation which lasted through dinner and well into the evening.
I told my friend what I had learned about the "Liquid Bombers" and their plot, their arrests and trials, and their coded emails. Holmes listened quietly for quite some time before he started asking questions.
"It is ironic, is it not," he said, "that the plot as described by the Crown was so far-fetched as to be practically impossible, and yet the plotters themselves appear to have been very earnest about it."
"Clearly they did not understand the technical difficulties," I replied. "I have been getting the impression that some of them were not very bright."
"What does that suggest?" he asked.
"I can't say it leads me anywhere," I admitted. "What does it suggest to you?"
“Put yourself in the shoes of a terrorist recruiter,” he replied. “Suppose you were trying to organize a bombing plot. What sort of people would you seek out?”
“I’d look for competent people, with intelligence and discretion,” I replied after a moment's thought.
“Exactly,” said Holmes. “But what if you were simply trying to perpetrate a hoax of some kind?”
“In that case,” I answered, “I would do everything I could to avoid intelligent people. I’d want to find people who were not smart enough to realize they were being deceived.”
“How many knuckleheads do you count among the plotters?” he asked.
“Three, four, maybe five,” I said, and my friend nodded. “Are you saying it was a hoax, then?” I asked.
“We would be wise to keep the possibility in mind,” he replied. “I think we should also be aware of the possibility that the prosecution may have made wildly exaggerated claims.”
“Well, it's clear that no bombing attack was imminent,” I said, “but are you thinking of anything else?”
“Above all,” he answered, “I am highly skeptical of the claim that the plotters boiled down hydrogen peroxide to a concentration of eighty percent. Such a procedure would be extraordinarily dangerous, and the resulting liquid would be virtually impossible to store.
”Peroxide is used in some industrial processes," the detective continued, "primarily as a bleaching agent. If you or I, or the terrorists, had the proper credentials, we could buy it at industrial strength, which is normally forty or fifty percent. And if we did so, we would find that it came in specially designed bottles."
"Why is that?" I asked.
"Hydrogen peroxide is inherently unstable," he replied. "It breaks down spontaneously, yielding water and oxygen. The latter, of course, is a gas at room temperature, and the pressure it produces would rupture any container not designed to hold it. This is why industrial grade peroxide is sold in heavy bottles with pressure-release caps. When the pressure gets strong enough, a valve in the cap opens and releases some of the oxygen. Otherwise, concentrated peroxide would be too dangerous to be used for anything at all."
"And yet," I said, "the plotters were planning to inject it into sports-drink bottles whose caps had never been removed, then seal the bottles with glue."
"They would have been somewhat better off with soda bottles," said Holmes, "since those are designed to hold some pressure. But in any case, their plot, as described by the Crown, was certainly doomed to fail. Even if they could have hollowed out batteries and filled them with homemade explosives, they still wouldn't have stood a chance."
"At the first trial," I said, "the jury was shown a video of a bottle of hydrogen peroxide exploding. At face value, it seemed to indicate that the plot was viable. But on cross-examination it emerged that the bottle that exploded was prepared by the police, not the plotters; that it was assembled by a remote-controlled robot because police explosives experts believed it was too dangerous to assemble by hand; and that it took them several dozen attempts before they got one right."
"Let that serve as the last word on the viability of the plot," said Holmes.
"That's fine with me," I said. "What can we do now?"
"I may need to be away for most of the weekend," he replied. "Are you willing to do some more reading?"
"I'll do whatever I can to help," I answered.
"That's the spirit, Watson!" he said. "I would like you to look into another case. What, if anything, do you know about Operation Pathway?"
"As I understand the term," I replied, "it denotes a campaign of roadside spot-checks to make sure drivers haven't been drinking, and that they have their seat belts fastened. Surely there is no connection between this and the Gareth Williams case?"
"No indeed," said my friend. "But the same name was used for a counter-terror surveillance operation which resulted in a dozen arrests, but no charges. Those who were arrested were allegedly in contact with Rashid Rauf via email."
I whistled softly.
"Fortunately," Holmes continued, "I have a collection of relevant news reports. As you read them, keep in mind the same questions I asked about the 'Liquid Bombers.' Find out everything you can about the plotters and their plot, the circumstances under which they were arrested, and the emails they sent and received. Excuse me for a moment, will you?"
For a few seconds I heard him rustling through the drawers where he kept his files; then he returned with a thick folder in hand. "I need to leave early tomorrow morning," he said. "And I will probably be away until late Sunday or Monday. That should give you plenty of time to digest this."
"I will do my best," I said, taking the file he offered.
"You have been doing excellent work, my friend," Holmes replied, "and I have every confidence in your abilities. Take your time, learn what you can, and we will talk again when I return."