“Cautious motherfucker, aren’t you?”

“Ten minutes,” he replied, “and then we’re out of here.”

Davidson nodded and headed toward the bedroom.

Opening up the double doors beneath the sink with the toe of his shoe, Vaughan bent down and looked for another towel or a rag of his own. There were certain places you didn’t want to be linked to. An apartment you broke into without a warrant was definitely one of them, followed closely by a residence belonging to a Muslim cab driver who had a fondness for Sayyid Qutb. Nothing but trouble could come from being connected to this place.

Under the sink, he found a white plastic grocery bag stuffed with more of the same white plastic bags. In the center was what looked like a pink towel. He emptied the lot of them onto the kitchen floor only to realize that the pink mass in the center wasn’t a towel but a folded shopping bag from a beauty supply store.

It was an odd item for Nasiri to have. Maybe someone had left it in his cab. Or maybe Nasiri had a girlfriend. If they could locate a girlfriend, they might be able to locate him.

Vaughan unfolded the bag. There was a silhouette of a woman with perfectly coifed hair and the name, address, and phone number of the store. Vaughan opened the bag and looked inside. He found a receipt dated two days before the accident. Nasiri had purchased only one item, but multiple bottles of it.

Vaughan began going through the other bags looking for receipts. He didn’t find a ton, but he found enough and they were very interesting.

In addition to purchasing hydrogen peroxide at the beauty supply store, he had also bought more of the same, along with drain cleaner, at grocery stores and pharmacies. He included other odds and ends to try to mask what he was doing, but Vaughan knew what he was up to. Nasiri wasn’t giving out dye jobs and throwing drain-cleaning parties for his friends.

Davidson stepped back into the kitchen and saw Vaughan with the plastic bags. “What’d you find?”

“Do you know what the mother of Satan is?”

“No idea,” said Davidson.

“Triacetone triperoxide. TATP,” said Vaughan, holding up the receipts.

“Should I know what that is?”

“It’s also called acetone peroxide. It is an explosive popular with terrorists. Its ingredients are very easy to get. The two most important things you need to make it are hydrogen peroxide and sulfuric acid.”

“Where do you get sulfuric acid?”

“Drain cleaner,” said Vaughan, holding up the receipts. “It looks like every time he goes to the store, he picks up a bottle or two, or sometimes even three. He appears to have been doing it in small batches so as not to raise suspicion.”

“And fly right beneath the radar.”

Vaughan nodded. “Exactly. It’s called the mother of Satan because it is so volatile. One of the ways we could spot bomb makers when I was in Iraq was because the best ones were missing fingers, sometimes even hands.”

“The best ones were missing fingers or hands? That doesn’t make sense.”

“They were the ones who learned to respect their craft. Lose a finger, or two, or three and you become incredibly conscientious. Lose a hand and you’ll probably end up being an instructor.”

“Is that the stuff that was used in the London bombings?” asked Davidson.

“Yup. It was also part of the shoe bomber plot, the 2006 transatlantic plane bombing plot, the underwear bomber plot, and what that Afghan named Zazi they busted in Denver was working on.”

“So Nasiri is a bomb maker?”

“That, or he was acquiring the ingredients for someone else,” said Vaughan. “Either way, this is probably the real reason he took off after hitting Alison Taylor.”

“So what do we do now? I’m no lawyer,” Davidson stated, drawing the word out, “but that evidence is definitely fruit of the poisonous tree.”

Even though his metaphor was a bit mixed up, he was right. Evidence obtained through an illegal search, seizure, or interrogation was known as a poisonous tree. Any evidence later discovered because of knowledge gained from the first illegal search, seizure, or interrogation was known as the fruit of the poisonous tree. None of it would be admissible in a court.

It would also be impossible to get any warrants based on it. This put the officers in a very difficult position. Nasiri was up to no good, but legally their hands were tied. They couldn’t share what they knew about the bomb-making ingredients.

While the mechanic’s information had been given under duress, they probably could get a warrant with it and come back, but someone across the alley had already seen them enter the apartment. As far as the apartment was concerned, they were dead in the water.

“We’re definitely impounding the cab. Somehow, there’s got to be a way to get it tested for bomb residue. If we get a hit, then everyone is going to climb on board this case.”

“Let’s say you do figure out a way to bury our poisonous fruit and get them to test the cab. What if there’s no residue?”

“It doesn’t matter. We can’t give up. We’ve got to stay on this guy. We legally obtained his name and photograph. We can put those out across the PD and I’ll reach out to a guy I know on the Joint Terrorism Task Force. I’ll have him pull all the flight records and see if Nasiri has tried to board any aircraft.”

“And if he hasn’t?” asked Davidson.

“Then we should assume he’s still in the city and that he’s not planning on taking his bombs back to Pakistan with him.”

Davidson looked down at the half-eaten plate of food. “We should also assume he’s not coming back here.”

“Agreed. So if you were him, where would you go now?”

“Someplace safe.”

Vaughan nodded. “Someplace with people you could trust.”

“Like members of your terror cell?”

“Bombers tend to need support, so I’m willing to bet there’s a cell.”

“But how do you track it down?” asked Davidson.

“We may not have to,” replied Vaughan. “Let’s finish up here and get back to your truck. I want to see if Nasiri will lead us to it all by himself.”

Abdul Rashid’s cell phone vibrated again. He held it up so the man sitting across from him could see it.

Rashid was in his mid-twenties with dark hair and a handsome, angular face. He was lean and stood about six feet tall. He had green eyes, an unusual feature that marked his mixed Arab descent. “The longer we ignore him, the more dangerous this gets.”

The man gave a dismissive, backhanded wave.

“That’s your answer?” asked Rashid. “Are you serious? You know what? Fuck you, Marwan.”

Rashid stood up from his cushion and threw his cell phone at the man.

Marwan Jarrah, a man in his late fifties with gray hair and a neatly trimmed salt-and-pepper beard, dodged the phone and smiled. He loved the younger man’s passion. Rashid had more than earned the right to be so outspoken. He was one of the very few true believers who could effortlessly stroll among the infidels without raising their suspicion. His methods of waging jihad were often unorthodox, but they were also brilliant. It was why Jarrah kept him close. It was also why Jarrah tolerated Rashid’s impulsiveness and foul language.

Blessed with a Caucasian father and an Egyptian mother, Abdul Rashid possessed a mixed set of features. Those features were such that Westerners never saw him as an Arab, or as being distinctly Muslim. To them he appeared perfectly American, while to Muslims he looked Arab. Such was the magic gift of his parents’ combined DNA.

With family scattered across the Muslim world, he had a backstopped cover for the extensive trips abroad where he studied in some of the most rigorous and extensive mujahideen camps. Marwan had personally witnessed him gun down two Jordanians who had tried to double-cross them in Iraq. Though they had known each other for only a couple of years, he was proud to call Rashid his brother, even though he was more like a son. The man’s experience and skills were beyond question. So talented was he, and so beloved, that he was referred to in Arabic as Shahab-a bright star that illuminates the heavens.