"Do you think I need a primer on Vaja Nikoladze?"

"And," continued Heat, undeterred, "he was being spied on by my mother."

"Here's all you need to know about Nikoladze," said Agent Bell. "He's been a credible and productive informant in our system for years. Plus, our biochemist is in a disarmament think tank that promotes the demilitarization of science. If anything, your mom was using Vaja as an expert source."

"You were the FBI liaison with my mother back then," said Nikki to Callan. "Was that the relationship?"

"I honestly couldn't tell you one way or the other."

"Then I want to find out."

"No, you want to be right and me to be wrong," Yardley said. "Stop wasting time."

Bell stalked out of the room. Callan said, "Heat, maybe there are more productive lines of investigation to focus on."

"Sounds like an order." The DHS man didn't answer, except to smile. Nikki said, "Silly me. Here I was afraid if I joined your team I'd find it full of infighting and dysfunction."

Captain Irons made a show of turning his back on Heat to stare out at 82nd Street when she returned from the DHS meeting. Somehow, she'd be able to live with that. She got to her desk, woke up her monitor, and began clearing acc.u.mulated e-mails. There were a few progress updates from the squad on the serial killer, but most of her inbox brimmed with statements taken throughout the five boroughs from Rainbow pretenders. Nikki concentrated on the reports from her own detectives while she stirred the strawberry compote from the side cup into her two-percent yogurt.

"I had a real lunch," said Rook as he sauntered over. She moved some files from her desktop before he could sit on them-and just in time. "No yogurt on the fly for this man."

Roach came over, pa.s.sing a basketball, a long-standing brainstorming habit of theirs. Ochoa said, "Writer Boy's been a sulky boy."

Rook ignored them and went on about his lunch. "I took myself for a chilled seafood salad over at Ocean Grill on Columbus."

Raley caught Ochoa's pa.s.s. "He's all bent because you went to the DHS deal without telling him."

"A white tablecloth and real silverware." He leaned toward her. "Excuse me, is that plastic spoon cracked?"

"Rook," she said, "are you really bugged?"

"No, why should I be bugged?"

"Trust me, we had to listen to him. He's bugged," said Rales, who then pa.s.sed the ball to Rook, who flinched instead of catching it.

While Ochoa s.h.a.gged the ball from under a desk, Rook blurted, "All right, I didn't go to Ocean Grill. I lost my appet.i.te. A task force, Nikki. How could you go to the DHS Task Force without me?"

"Because it's restricted."

"Like that's ever stopped me." From anyone else, it would have seemed like an empty boast.

Detective Ochoa said, "My partner and I have been tossing around the idea of this van, the one that had Nicole Bernardin's blood and traces of lab cleaning solution in it. No sit-down lunch for us, either."

"What did you come up with?"

"OK, follow this," said Raley. "Let's suppose, like you said at the briefing, that Nicole Bernardin picked up some sort of biological toxin on herself while she was checking out whatever Tyler Wynn was into. Whoever caught her snooping around and killed her must have worried her body might register telltale contamination."

Ochoa picked up. "Which is why they scrubbed her corpse before they dumped it. They didn't want to set off any alarms."

"And since Carter Damon's van had both Nicole Bernardin's blood and traces of lab cleaning solvent," continued Raley, "I think it's a good bet that van got used to transport her body from where she was stabbed and scrubbed to where she got left in the suitcase. So our thinking is, if we can figure out where Damon's van traveled the night of her murder-"

"-We might just find the bioterror lab she discovered," said Heat. She added a "might" but liked this feeling, the little spark that could possibly kindle a break.

"But how could you ever learn where the van traveled?" asked Rook.

Detective Feller chimed in from his desk. "Doesn't Homeland Security have cameras that scan license plates at key intersections and toll plazas so they can track suspicious vehicles that enter and drive around the city?"

"They do. They'd have video archives," Raley said. "So would NYPD."

Heat thought about the experience she'd just had in the bunker and said to Roach, "Start with NYPD."

"Your task force meeting was that good?" said Rook as Raley and Ochoa moved off to work the new lead.

"Shut up," she said, hiding her smile in her yogurt. "Let a gal enjoy her lunch."

"Sure. And while you do, let me share some thinking I tossed around with my partner. I'll admit it's an imaginary partner, which is why I'm so glad you're back."

"Rook, are you having a reality break, or does this have a point?"

"My point," he said, "is that if Tyler Wynn had so many foreign connections, why didn't he get out of Dodge instead of hanging around a month after you put the APB out on his traitorous a.s.s?"

"Simple. To see the plot through."

"That's where I b.u.mp. What was the first thing Wynn said to you after the blast?"

"He asked me if Salena Kaye did it."

"No, exact quote, please, Detective."

Heat pictured the old man down on the kitchen floor. It all replayed like a movie. "He said, 'Was it Salena? Did Kaye find me?' "

Rook said, "See, now that's not just big, that's an XL."

"He's right." Randall Feller couldn't resist joining the spitball and came over. "The 'find me' part sounds like Wynn was hiding out from his own accomplice."

Rook continued, "And if Salena Kaye turned on him, and he was still hiding in New York, it suggests that his own organization cut him off and he lost the resources to flee these borders undetected. I've seen this before with my European spy friends. One day you're center car of the motorcade, the next you're hiding in Dumpsters, afraid to show your face and unable to board an airplane."

"The question is, why did they all of a sudden want him dead?" asked Feller.

"I hope to find that out," said Heat. "Maybe because I compromised him by surviving. When I came out of that subway alive, Uncle Tyler got on somebody's. .h.i.t list because if we captured him, he might give up his co-conspirators."

"Good a reason as any," said Rook. "It also tells you why Salena hung around. To finish him off."

"And me," said Nikki.

"There she goes." Rook winked at Feller, then turned to Nikki. "It's all about you, isn't it?"

"Do you think Salena Kaye killed him?" asked Sharon Hinesburg. Randall Feller wasn't the only detective unable to resist joining the brainstorming session. But such engagement was rare for Hinesburg. Maybe she was trying to turn it around, after all.

"Kaye would certainly top the list," said Heat.

Feller crinkled his brow. "But isn't poison her MO of choice?"

Nikki said, "Best choice is the one that's effective."

"And we're sure he wasn't building a bomb and it went off on him?" asked Feller.

Heat shook no. "There weren't any bomb-making materials in his apartment."

"Please," said Rook in mock indignation. "This is Sutton Place we're talking about. The condo board wouldn't have it."

"Concierge records indicate a package delivered to his apartment," Heat explained. "Local messenger service, no trace. Probably bogus."

"So if he wasn't right beside the blast," said Rook, "the package probably wasn't rigged for opening."

"That leaves a timer or a remote detonation." Heat did another e-mail scan. "I'm still waiting to hear that determination. Forensics and Bomb Squad are both on that."

"You've got a lot on your plate," said Detective Hinesburg. "How about if I follow up and see what gives?" Nikki approved of the weak link trying to redeem herself and said sure.

Whether it was old-fashioned Heat Guilt or just to prove to herself that she could juggle it all, Nikki spent the rest of the day chipping away at the Rainbow case. She had finally surrendered to calling it that, which, hours later, const.i.tuted the only movement in the entire investigation. Satisfied that her squad remained diligent and engaged in the hunt for Rainbow, Heat allowed herself an indulgence. Like scratching poison ivy, she couldn't restrain herself, even though she knew the act would likely do more harm than good.

"Hallo, this is Vaja," said the man on the other end, whose soft voice and Eurasian inflections made her picture him in a Tbilisi coffee house reciting poetry.

"Dr. Nikoladze," said Heat in a cheery tone, keeping it casual, "Nikki Heat. How's dog business?" She could hear the breeze off the Hudson against his mouthpiece and the distant kennel sounds of his Georgian shepherds. "Am I going to be seeing you this winter at Westminster?"

"We had this conversation already, Detective. Good evening." The phone rustled, a dog barked, and the line went dead. "Call Ended."

She looked up from the blank gla.s.s of her iPhone screen, shaken out of her preoccupation by Rook, who had pulled on his sport coat and slung his Coach messenger bag over his shoulder. "I've got at least another hour or two to go here," she said.

"Yeah, I figured." He adjusted the wide strap of his bag to lie against the soft of his neck at the collar. "I got a call and have a meeting. c.o.c.ktails, and it'll probably turn into dinner." Nikki's solar plexus tweaked. In an irrational flash, she envisioned him and Yardley Bell in one of their spots. Boulud, Balthazar, or n.o.bu. Or, worse, one of the old Jamie-Yardley haunts from when they were a couple. "It's more magazine business," he said.

"Good stuff, I hope."

"We'll see. My agent has set me up with some movie execs from Castle Rock. Just exploratory, but they want to talk about optioning the Heat pieces for film."

Nikki would almost have rather it were candlelight and mutually fed strawberries with Yardley. Well, maybe not, but close. "Are you kidding me? A movie? Based on my... pieces?" She spat the word. The bull pen had mostly cleared for the night, but she kept her voice down anyway.

"Come on, this is nothing. You meet, you discuss. It's a dance. Nothing is set-or will be-without talking it over with you. You have my word as a member of the press." He laughed, trying to lighten the load with that.

She dismissed it with a hand wave, just to have it go away for now. The whole notion still chapped her, but Nikki made a tactical surrender because she couldn't bear the strain of one more ounce of conflict in her life. But she knew this tin can was only getting kicked down the road. "I get it. Fine, really." She stood and hugged him. "After spending a night on the couch here, I'm going home to turn in early, so why don't I see you in the morning?"

He leaned in. She gave him an office-appropriate kiss, watched him go out, and sat five minutes just to meditate herself calm.

Nikki came home with a to-go bag from Duke's around the block. During a comfort supper of Ma's Macaroni and KC Sloppy Ribs, Heat caught some baseball on TV. After her bath, the fans were just getting to "Take Me Out to the Ballgame," and she coc.o.o.ned on the couch wrapped in a throw blanket while she battled sleep trying to stay awake for the late innings. Sleep won.

The phone woke her. She muted the postgame report and picked up her cell. The ID said "Unknown Caller."

"You had to know you'd be next," said the Darth Vader voice.

Rainbow.

Jolted, her heart pounded. She stood, pulling her bathrobe around herself, a primal reflex. "You're calling after office hours," she said, trying to mask the vulnerability she felt with some edge. The home call to her personal cell had done its job. He'd spooked her.

"Maximizing time," he said. "Who knows how many hours you have left? Well..." He chuckled. "Actually, I do."

"You're going to be disappointed."

"Could be," he said. Even through the electronic scramble, she could hear the earnestness of his admission. "You're a challenge, Heat. Like I said, you're smarter than the others." He paused slightly, then added, "But know what? It makes me wonder."

"What do you mean?"

"That you still don't know. That's what I mean." Then he hung up.

Heat felt like she should do something, but what? If she called to report this to Irons, he'd smother her with a protection detail or, worse, sideline her entirely, as he had a month ago with the enforced psych leave. Calling Detective Feller came to mind, as did Raley and Ochoa-all of whom had shown at one time or another what it meant for one cop to have another's back. But she didn't want to set off alarm bells or distract them from their work chasing leads. Same with calling her local precinct. The Thirteenth had covered her front door before with a blue-and-white, but once again, that could send ripples back to Captain Irons. Rook? She checked her watch. Almost 11 P.M.

She speed-dialed him, knowing he'd be more company than protection, but company would do nicely. He picked up on the third ring. "Hey, what's going on?" Rook spoke in a low voice, subdued, the way she had seen him take calls when he was somewhere he couldn't really talk.

"This a bad time?"

"No, not at all." She could hear silver clanging and table conversation, something like "Nathan would be perfect casting, if he's available." Nikki sensed his palm cupped around the mouthpiece. He said, "Just doing some spitballing with the Castle Rock folks. Can I call you in ten or fifteen? You gonna be up?"

"That's OK, stay on your meeting. I just wanted to say good night."

"Good night to you, too." She could hear the way he tried not to sound stilted-and his disappointment that he did nonetheless.

"See you in the pen in the A.M.," she said. Just hearing his voice had soothed her nerves. She made a double-check of her front door and all the windows, then went to bed with her Sig Sauer unholstered on the floor by the nightstand.

Sweet exhaustion took her, and she floated in a luxurious descent into the rabbit hole. An e-mail ping on her phone woke her at seven. Nikki twisted up on one elbow to check it. Agent Callan requested a conference call that morning. She tapped in a yes, then flopped back and stretched, drawing in a long, refreshing chestful, wishing she had asked Rook to come over. She turned to look at his pillow and sat up, quaking in alarm at what she saw resting there.

A coil of orange string.

TWELVE.

"Tell me this really didn't happen," said Rook. "You let a serial killer touch my pillow?"

Heat laughed for the first time in days. When her laughter choked in her throat and she stifled tears, he held her, and Nikki let herself fold into him, wrapping her long arms around his back and pressing a cheek against his chest just for the grace of hearing a loving heart.

A throat cleared behind them. Benigno DeJesus, from the evidence collection team, stood in her open apartment doorway. Behind him waited his crew, also suited up in lab coveralls, footies, gloves, scrub hats, and masks. Rook said, "Love the costumes, kids, but the last trick-or-treaters got all the gummy bears."

DeJesus hadn't pulled his mask up yet, but even that wouldn't hide the grimness he exuded because of the nature of this visit. He greeted Nikki warmly, although they didn't even attempt to shake, each being an old pro at the contamination drill. "I'm glad it's you," Heat said, and not for the first time. She'd never worked with a better forensics detective than Benigno, and had requested him when she put in the call.