"I'm serious. Without your special relationship with Yardley Bell, we'd never have this lead." Separately, Heat and Rook reacted with discomfort. They both wanted out of that car, but doing fifty in a Code Three wouldn't be the place. And Bart continued, sounding innocent even as he made one last pick at the scab. "You and Yardley must be good friends to have ended a romance and still be this close." Rook didn't answer that. Heat wanted to turn in her seat and eyeball him; wished for one moment of privacy so she could unload. That would wait.

"Know what this bridge is?" asked Callan as they crossed the Harlem River on the Willis Avenue span. "The twenty-mile-mark of the New York City Marathon. Know what we call this bridge? The Wall."

"Because this is where you hit it?" asked Rook.

"No." Callan scoffed. "Because this is where the lesser runners do."

An officer in black fatigues waved them into the staging area, the parking lot of the US Postal Service's Bronx sorting facility off Brown Place, around the corner and out of sight of Barrett's Do the Jerk warehouse. Callan scoped the blacktop, which was filled with hazmat vans, FDNY trucks, ambulances, and a pair of daunting, black military-style armored personnel carriers with battering rams. In a far corner, a portable hazardous materials scrub-shower area was being set up beside a medical DRASH tent. "Handy to have this USPS property here in the neighborhood," said Heat.

The agent nodded. "This is federal synergy at its finest." He sounded tongue-in-cheek, but his face meant every word. When they heard the click of Rook unbuckling his seat belt, Callan found him in the rearview mirror. He spoke softly but with the tone of a drill instructor. "You will remain in the vehicle." Rook folded his hands in his lap to wait.

Yardley Bell met them mid-block on 132nd, on their walk-up to the deployment zone, and recited the briefing. "Streets are cordoned, all exits blocked, neighboring properties... a shipping fulfillment center and a scaffolding business... have been cleared out. Quarantine team's ready and we have air support." She twisted to the sky. "We also attracted a couple of TV news choppers. I had FAA push them back one mile, and our public information officer is calling the stations to inform them of the readiness exercises we are conducting this week." Nikki listened to Yardley, so in-charge. She heard the competency and the confidence, and felt a little bad she couldn't admire her.

"Got your warrant, Agent Bell." Callan handed her the paper.

She gave it a quick glance and said, "Let's light the fuse."

They approached the front gate using one of the box trucks borrowed from the US Mail, the driver announcing a delivery for Algernon Barrett. The fence rolled back, admitting Mr. Barrett's delivery: a dozen armed federal agents Trojan Horsed in the cargo hold. The personnel carriers, Crown Vics, and half a dozen white vans marked with the blue vertical Homeland Security stripe drafted in behind it.

Bell went in first with a SWAT team, her badge and the warrant lofted above her head. She announced herself and ordered everyone to stay as they were, showing their hands. Detective Heat entered in the second wave, along with cooperating law enforcement and a platoon of biotechnicians lugging portable aerosol sniffers and other sensory gear. Once past Reception and the front offices, the rest of the facility appeared laid out, open plan, in one story under a corrugated roof. With no resistance and n.o.body fleeing, agents easily corralled the thirty startled employees near the loading dock while the DHS techies dispersed to sample air and inspect equipment and storage containers.

Because of her firsthand knowledge of the layout, Heat led Bell to Algernon Barrett's office. The Jamaican was gone, but the betting line for the upcoming Kentucky Derby blared from his big-screen TV and a pungent wisp curled up from a fatty in the ashtray. Both of them poised their hands on their holsters and cleared the private bathroom. The other door in the office gave onto a back hallway leading to the warehouse. Outside a door marked as the spice supply room, they took ready positions and entered. "Looky here," said Yardley Bell as Barrett emerged from between stacked cartons of Scotch bonnets and cloves with his hands up. "I found the secret jerk ingredient."

They searched him and took him back up the hall to his office. Nikki had warned them before they left Varick Street about Barrett's lawyer, so they were eager to get some interrogation happening before Helen Miksit complicated matters.

"Why did you hide?"

"Who are you?"

"Bart Callan, special agent in charge, Department of Homeland Security. Just one of the people in this room who can make your life h.e.l.l. Now, answer my question. Why did you hide from us?"

"Habit, I guess. Doors get busted, man's got to run."

"You expect us to believe that?"

"Believe what you like, mon." Algernon turned from him and surveyed Nikki, who stood off in the corner, still wearing her Homeland hoodie. "So, Detective, this is what I get for cooperating?"

Nikki said, "Mr. Barrett, this will all go more smoothly if you continue to do so."

"Yeah?" He folded his arms and leaned back on the couch. "I'm not saying anything. I want my lawyer."

An hour later, after Callan and Bell did their best to brace him both head-on and sideways about his partic.i.p.ation in a terror plot, they lost him to the Bulldog, who advised her client to say absolutely nothing. Her statement, she said, would suffice. "My client is a United States citizen and taxpayer. He operates a successful, legitimate business purveying spice rubs and chicken dishes to a loyal public. Any inference that he is involved in some sort of diabolical plot based on his foreign origin is wild speculation, offensive, and slanderous."

"What about his sudden expansion at key targets of opportunity?" asked Bell.

"They are targets of opportunity," said Helen Miksit. "For profit. So unless you have evidence or a charge to file, why don't you suck it?" If nothing else came out of this raid, Nikki thought that, just maybe, she could get to like Helen Miksit after all.

Out in the warehouse, while the forensic technicians continued their search for evidence of viral or bacterial agents in marination canisters, drums of spices, and refrigerators, Heat took Callan aside. "If it's all the same to you, I'm going to bag this and get back to my precinct."

"I so was hopeful this would give us traction." He surveyed the activity, ending with a head shake. "Heat, we need a break."

"We do. I just never felt like it was here."

"Is that an I-told-you-so?" Yardley Bell, from ten feet away, handed the company's shipments manifest back to an agent and came over to join them. "See, Detective, here is the fundamental difference between us: You're ready to bag it because it didn't just land in our laps; I am ready to double down." She turned to Callan. "Pull me some more warrants, Agent. I want to toss Barrett's house, I want to toss the houses of his friends, his dealers, his hookers, his f.u.c.king pastor. I am ready to rattle some cages." She walked away backward, saying to Nikki, "And then, if we survive to Monday, I can be an I-told-you-so."

Callan arranged for an agent to shuttle Heat and Rook back to the Twentieth, which only further postponed the conversation looming over them about Rook's loose lips. He filled the trip mostly by complaining about his Callan-forced SUV time-out. "I hated that. I felt like I was sitting in the penalty box, having to watch a power play. Anyway, I made use of the hour and a half getting my mother out of the city."

"Rook."

"Don't worry, I didn't tell her why. I'm much sneakier than that."

"I know."

He sidestepped that and explained, "I called in an IOU from a colleague of mine at the State University of New York and arranged for Margaret Rook, Broadway's diva's diva, to receive the first annual Stage Door Prize at the SUNY Oswego Drama Festival. It's short notice, but Mom's thrilled."

"What is the Stage Door Prize?"

"Haven't figured that out yet. All I know is it's going to cost me ten grand plus luxury accommodations. But it gets Mom out of harm's way. Just in case... you know."

She turned away and stared out the window as they turned off Lenox Avenue, remembering for a moment when she caught a glimpse of foliage at the north end of Central Park that it was spring. Her brief interlude with nature got interrupted by a text. "Weird," she said after reading it. "From Callan. Test results of the bioagent traces on my blazer came back. It wasn't ricin." She held out her phone to Rook.

"Smallpox?" His face turned ashen. "Didn't Dr. Doom from CDC call that one of the bad boys?" She nodded. "And all you can say is, 'weird'? Oh, excuse me, just a spot of bother. I seem to have picked up a bit of smallpox on my coat sleeve. No biggie."

"It is a biggie, I know it's a biggie. Apparently it's a marker, not enough to cause worry, but a medic is coming to give me a shot." She finished reading and said, "What's weird to me is that it's not ricin, so that means I didn't pick it up from Ari Weiss's corpse."

"So where?"

"I don't know."

There was a silence. Then the driver lowered his window. "Don't blame you, buddy," said Rook. "Stick your head out and breathe, if you like."

As soon as the DHS car dropped them on 82nd, Rook smiled and said, "So. We good?"

"That's it? That's what you call dealing with this? Shrug it off and say 'We good'?" She mocked him by brushing her palms as if dusting them clean. "G.o.d, you are such a boy."

"I am not..." He mimicked her palm brushing. "I just think we should be good because you know very well that I would never compromise you by sharing secrets."

"Then what do you call it?"

Sharon Hinesburg pa.s.sed by with a take-out bag, and they held their conversation. When she went inside the precinct, Rook said, "First of all, before I can keep a secret, I have to know it's a secret. I thought we were all kind of working on the same team here, trying to stop the bad guys from unleashing a plague."

"Being on the same team is one thing, Rook, but that doesn't mean you can go reporting to other people. Especially Yardley Bell."

"You don't like her."

"It's not about liking her."

"You're still jealous because we have a history."

"It's not that, either. I just don't trust her."

"Why not?"

"Nothing I can pinpoint. It's an instinct."

"Hey, I'm the one with hunches and instincts, and you hate that."

"Well now it's my turn. And as irrational as it may seem, I want you to respect that." They regarded each other a moment, and in spite of the argument, all the good feelings held fast. Maybe that's what a relationship was, she thought. She reached out and he took her hand. "Look, you know what I'm juggling. All I'm saying is, with everything else I have to look over my shoulder about, I don't want you to be another one."

He reached out his other hand and she took that, and they faced each other. He smiled. "So. We good?"

Heat regarded him and knew that, above all else, Jameson Rook was a good man she could trust. Nothing else mattered. "We are good." She squeezed both his hands and they walked in together.

While Nikki received her shot of an antiviral, she thought through her day for any clue where she might have picked up that smallpox marker. A disturbing notion came to her. After quick calls to Benigno DeJesus and Bart Callan, the orange string Rainbow left on the pillow got priority-messengered to the DHS lab for testing. A certain conspiracy-hungry boyfriend would be quite proud of her.

One thing Heat did know for certain: There was no way in h.e.l.l she would spend another minute in sweats at the cop shop. She opened her bottom file drawer where she kept what she called her emergency wear: backup apparel for those days she spilled coffee or got blood on her clothes.

After a quick change and a review of the Murder Boards, she decided it was time to hit the phones again. That was how an investigation worked. You got a new sc.r.a.p of information and followed it up by talking to someone about it. Sometimes you got another sc.r.a.p that moved you forward, sometimes not. But you kept making rounds, occasionally feeling like a tethered pony walking a circle at a kids' zoo, but you just continued plodding until something shook loose.

First call went to Carey Maggs at Brewery Boz. He came on the line sounding extra-Brit, which was to say deliciously cranky and jovial about it. "Catching you at a busy time?"

He chuckled, "Is there any other kind? You know, just running a business and saving the world in a failing economy. I'm like your Clark Kent, only not slim enough for the tights, I suppose."

She thought of the peace march he was sponsoring that weekend, and her heart ached wanting to warn him about the looming terror possibility, but where did something like that stop? There were hundreds of public events, conventions, bike-a-thons, and street fairs on the weekend calendar. Maybe if Rook optioned her article to Hollywood, he'd have enough money to give everyone in New York City an award at SUNY and get them all out of town. Putting that aside, she broke the news to Maggs about Ari Weiss: that his old friend had not died of a blood disease at all, but had been murdered.

"Christ in heaven," he sighed.

Weiss's murder was not only new information, the stabbing matched her mother's so closely that Nikki texted Maggs a picture of her killer, Petar Matic. She heard the chime on his cell phone as it arrived, then a deep exhale and some tongue clicking from Maggs's end as he studied it. "Know what? I have seen this guy."

"You're sure?"

"No doubt. It's the greasy long hair and the slacker eyes. Who is he?"

"He was my boyfriend."

"Uh-oh, low bridge, sorry."

"... Who killed my mother." She heard a whispered curse and continued, "It's likely he stabbed Ari as well. Do you recall when you saw him, and where?"

"I do very well because I called the police about him. He was hanging about in the front of my apartment building a number of times and I wanted him dealt with."

"When was this?"

"Good lord, Detective, it was near Thanksgiving. Same week as Ari was staying with us. And same week as..."

"It's all right, Carey, I know what else happened that week."

Heat could hear the strain in Maggs as he absorbed the startling news she'd dropped on him about his old friend. But she pressed forward. He could recover later. Right now, she needed a new lead. "Carey, I want your help with something, if you're up for it." He sounded emotional but croaked out a yes, so she asked, "You mentioned Ari wasn't real social or political. Do you recall if he had any colleagues in the science world with whom he was close? Was there anyone in particular he talked about, or teamed with on any special projects?"

After some thought, Maggs said, "None that stuck in my brain. Sure, I'd cross paths with his crowd for a beer or to watch football at Slattery's, but to me they were, basically, this blur of boffins."

She didn't want to lead him with a name, so she asked, "Do you recall any foreigners?"

He laughed. "You're joking, right? That was most of them."

And then she said it. But Maggs didn't recall any Vaja Nikoladze by name, so she texted him his photo, too, and waited for him to look at it. "Sorry. He meets the boffin test, but I don't remember him hanging out with Ari."

Nikki chalked up another disappointment, but at least she'd gotten her ID of Petar, firming up his connection to Ari Weiss's murder.

Rook convinced her to step out with him for a quick bite at the new Shake Shack that had just opened on Columbus, but they didn't get that far. In fact, Detective Raley called them to a stop in the precinct lobby. "What's up, Sean? You spot something on the Coney Crest tapes?"

"No, still screening them. But Miguel and I just got a hit on something else. Trust me, you will want to see this."

"I think the Shake Shack will have to manage without us," said Rook.

When Heat came back into the bull pen, Ochoa had the results up on his monitor at Roach Central, which is what the pair had dubbed the corner where they had pushed their desks. "OK," he said as Heat sat in his chair, "we've been scouring the NYPD license plate surveillance cams from last month for any sign of that van that was hauling around the body of your mom's spy partner. We track the van, we find the lab, right?"

"We do," said Rook.

"We hope," said Heat.

"We scored," said Ochoa. "Big-time. Here's the first hit. And yes, it's from the night she was killed. " He clicked the mouse and a blurry image of the plate came up. The location read, "E-ZPa.s.s Lane 2, Henry Hudson Bridge."

"Is this right?" asked Heat. "All the way up there?"

Roach nodded in unison. "It's correct," said Raley.

"But we wondered the same thing," added Ochoa. "We asked ourselves, What's the van-and the body-doing coming down into the city from way up there? So we ran some further checks."

"I love you, Roach," said Heat.

Raley continued, "We combed a net of traffic cams at on-ramps in Westchester County and north."

"It wasn't as hard as it seems, since we knew the general time and exact date." Ochoa clicked again and the screen filled with four shots of the same plate at different locations. "So, backtracking, here's where we see the first appearance of the van on its drive south toward New York City." He double-clicked the top image. When it opened, the location stamp made Heat gasp.

FIFTEEN.

That maroon van could have been coming from any number of places when it got photographed getting on the Saw Mill River Parkway at Hastings-on-Hudson, but Nikki Heat could only think of one. Rook said it out loud. "Vaja." In a single mouse click all the reasons-all the instincts-she'd had about holding on to the biochemist as a person of interest seemed to be borne out. Heat only prayed it wasn't too late.

"Roach, saddle up." She turned to the other detectives in the bull pen. "Feller. Rhymer. You, too. We're taking a ride to Westchester."