"Naturally, I wanted to know if Summers had heard from him."

"And?"

"He hadn't."

"And what else?" Bell's gaze didn't waver.

She knew the best strategy was to tell the truth. Since Nikki would never give up the code, she did the next best thing. She told a truth. "Tyler Wynn has very specific tastes, and we wanted to get a track on him through his consumer trail. We didn't know how far to trust Summers, so Rook used the cover of picking his brain for a magazine article to get the specifics we needed." Heat stopped there. She'd seen so many people over-talk when they were on thin ice, when the best thing to do is get off it-and fast. She sat back in her chair and let them work.

"So this would be Rook's version, too?" asked Callan.

Nikki shook her head derisively. "Version?" She stood and asked them to follow her.

The pleasure Heat hoped to get out of putting it in the agents' faces by leading them inside Rook's retail tracking center was quickly offset by his reaction to seeing Yardley Bell. And hers to seeing him. Nikki couldn't write a clear caption to their expressions. Was it just the way old lovers looked at each other, or were these the smiles of unfinished business? She stepped right between them and said, "This is the makeshift command post Rook has set up with Detective Rhymer to pick up Wynn's consumer trail."

"Quaint," said Agent Bell.

Heat said to Rook-and pointedly, "I was telling the agents how you and I met with Eugene Summers for the purpose of getting this enterprise going."

"That's right," he said. "And we'll see how polite the Maven of Manners is after he finds out his in-depth interview wasn't for any article." Smart. Even if Rook hadn't picked up on her cautionary note, he knew enough to be circ.u.mspect.

Yardley Bell said, "I'd like to see what your process is, Jamie." She turned to the others. "Could you give us a moment?"

Heat didn't like getting split up. Not tactically, not personally. But when Rhymer slid out with his Diet Pepsi and half-eaten club, Callan held the door for Nikki. She hesitated and left, too.

Alone again in the captain's gla.s.s house, Heat said, "So, was divide and conquer part of your drop-in strategy?"

"For the record, it wasn't my idea to come here to brace you."

"Who's running your case, Agent Callan?"

"It gets complicated. It's my office, my control, but Agent Bell packs major Beltway clout. She Bigfoots my whole day whenever she gets a wild hair." He threw his palms open. "And here we are."

"This is why I told you I didn't want to get tangled up inside your little investigative community," she said.

"I want to talk to you some more about that."

"You can save it."

"What if I said I agree with you?" He waited while she had time to absorb that surprise. "That's right. I've been giving it some thought since our c.o.c.ktails the other night, and I don't think it's a good idea for you to be on this team."

She studied him warily. "Just like that, you change your mind?"

"More like a change of heart." He rolled his chin to the gla.s.s like he didn't want an interruption. Or scrutiny, maybe. "Heat, I think I'm feeling a little personal about you, and that wouldn't be good for a close working relationship."

"Right," she said immediately, but then felt at a loss; not prepared for this, not at all.

One teenage summer on Cape Cod she had gotten it in her head to teach herself to windsurf. Starting after breakfast and going until sundown, Nikki's day did not become the blissful, athletic sail she had envisioned. Instead, it devolved into a relentless series of crashes, spills, and wipeouts punctuated by mere seconds of balance until a sudden gust or rogue wave pitched her into another endo. Nikki stared at Bart Callan and wondered how her entire life had become like that day. Of all the curves she'd been thrown lately, of all the complications she had pulling at her, this one could be the most damaging. She sensed jeopardy if she mishandled this.

"I didn't want to say anything about it, but I know you sort of got the vibe," he said, then waited for her to respond. She didn't, so he continued, "I sure got it from you."

And there it was. The second wave, the blindsider. Had she flirted? She sure didn't feel she had. Did she have a few "what if" thoughts? Who didn't? As she regained her center, Heat knew exactly what she had to say. "Bart, you need to know something." She made sure the eye contact left no ambiguity. "I am in a relationship now." She didn't elaborate. Didn't tell him he was a nice guy or anything that might leave a door open or be subject to interpretation. For good measure, she added, "It's important to me."

He nodded and said, "I hear you."

She smiled. "Good."

Then his gaze swept to the hallway where Yardley Bell stood in close conversation with Rook. "But let's keep in touch." He looked back at Nikki and said, "You never know."

As soon as her surprise company departed, Heat jumped back into the pressing business of hunting the serial killer. It wasn't until nine that night, in the back of the town car he had ordered to drive them to his loft, that they were able to connect. "What did you and Agent Yardley talk about?"

"If you're wondering if I mentioned The Thing, I didn't mention The Thing. Give me some credit."

"Maybe some," she said, wrapping it in a tease. "But seriously, you did make a quick pickup of my Eugene Summers meaning."

"Hey, I can be as duplicitous as the best of them. Except with you, of course. With you I am an open book, especially between the covers." He wanted to be playful. Heat wanted to be rea.s.sured.

"Then what did you two talk about?"

"Well, per her request, I gave her a quick primer on my Tyler Wynn project."

"How much?" Heat chafed at this interference in her case. Callan called it: Bigfoot.

"Enough to find out I may be chasing my tail. Like you, Yardley pointed out he used numerous aliases, plus the fact that he might be doing his shopping through some third party."

"So that's her contribution? To basically p.i.s.s on your investigation?"

"No, actually, she was quite helpful. Nikki, she gave me this brilliant new strategy to follow." If Rook had a clue how much his exuberance chapped her, he didn't let on. "Yardley says more and more retailers are using RFID technology."

"Educate me."

"Radio frequency identification. You know how your E-ZPa.s.s lifts the gate at a highway toll booth, or a security tag on a leather jacket sets off an alarm in a department store? Those are transponders that emit radio signals. Well, technology has now shrunk them down to chips smaller than a grain of rice, and manufacturers and retailers are planting them in their products for inventory control and consumer research. And how do they do that?" He paused to frame the significance. "They electronically track the chips to see where their products are distributed geographically." He slapped her thigh to punctuate his excitement.

"You're scaring me, Rook, going all geek on me."

"I can't help it. Don't you see? Of course you see. If we find enough products on the Tyler Wynn list that have RFID chips embedded in them, the little transponders could lead us right to his door, no matter what name he used."

Begrudgingly, reservedly, but, in the end, objectively, Heat admitted Yardley Bell's idea had merit. She told Rook she would a.s.sign more manpower and resources to the task first thing in the morning.

"And can you call it a task force?"

"No."

"I've always wanted to be on a task force."

"You'll have to save it for that video game you play in your boxers."

He turned away, watching Bryant Park go by his window. "Why do you hurt me?"

Upstairs in Rook's kitchen, he put some flame under a pot of water for angel hair to go with his scampi while she poured the Sancerre. Without naming it, they had taken to eating meals in more since the poisoning attempt. On high alert was not the way either wanted to live, or admit to living. "How you holding up?" he asked.

"Not exactly brain-dead. But I'm working on it."

He lifted his gla.s.s. "Here's to the living brain-dead. Makes you almost a zombie." After they toasted, he said, "If you want to kick back and take a shower, I'll keep busy sweating some garlic and sauteing these shrimp."

"You know what I'd really like to do?" she said.

"I do. You want to take another shot at The Thing."

"Rook, we're alone. We can call it the code."

He put on a mock pout. "Oh, you mean the code. I was hoping when you said you wanted another shot at The Thing..."

"You disgust me," she said with a laugh.

As she walked to the back hall, he called out, "I hid a copy in my office. It's in the top filing cabinet drawer under 'Nikki's Top Secret Code.' " And then she could hear him laugh.

Wide awake at 4 A.M., Heat eased out of bed, pulled on some gym shorts and a workout top, and slipped out of the room. Minutes later, she walked barefoot across Rook's rooftop and sat on the wall to stare at the city that also didn't sleep much.

The spring thunderstorms forecast for that morning hadn't arrived yet, but ominous clouds rolled in from the west, swallowing the ambient light of New York City and spitting it back the color of spilled blood.

Nikki fought despair. Out there in those concrete canyons a serial killer roamed free. So might the man responsible for her mother's murder. Not to mention his accomplice, who almost killed her. Heat looked all around, felt vulnerable, then told herself she didn't care. She almost believed it.

So far, Heat had managed to rescue one target of the serial killer, but still had no solid leads-nothing she'd call traction. Her quest for Wynn and Kaye remained stalled, with the added attraction of federal meddling: Bart Callan, vigorous, competent, and misguidedly personal; Yardley Bell, disruptive to Nikki's case and threatening to her relationship.

Downstairs in Rook's bed, Heat had tried to clear her mind of these demons. Since she couldn't sleep, she decided to be productive and mentally projected the lines, dots, and squiggles of her mom's code on the pale canvas of the ceiling. The solve still would not come.

So she changed the scenery. Resting a bare heel on the ornate scrollwork of the frieze beneath her, Heat listened to her breathing instead of the taxi horns, night sirens, and the doop-doop of garbage trucks at work. She let her eyes gloss over until she no longer saw the iconic Empire State and Chrysler Buildings looming out of the cityscape. Instead, her vision fused with the thin curtain of urban haze in the middle distance. Piano notes from her childhood songbook appeared and merged with the blurred apartment lights in the high-rises before her. Then those strange pencil notations surfaced like watermarks. Nikki could see the characters as clearly as she had on the page where they were written, so embossed were they in her mind's eye.

But whether studied on paper, a ceiling, or the crimson Tribeca skyline, they still told her nothing.

"How long have you been at this?" came the voice behind her. Nikki had wedged the access door open and didn't hear Rook come out on the roof.

She tilted to her right where dawn tried to muscle through the stubborn sky. "A couple of hours, maybe."

"Not tonight. I mean total." She didn't answer because he knew d.a.m.ned well how long. So he said, "Almost a month, Nikki. It's time."

"No." Heat said it so sharply pigeons flew. Much more measured, she added, "I'm not taking this to Homeland. Or Yardley."

"I agree."

"Then what?"

"You trust me, right?" he asked. "I mean really, really trust me?"

"What."

"I know a guy. A code breaker."

Heat didn't say no this time. She just continued to stare out at the city slowly coming to life. Then she nodded almost imperceptibly and turned to him for the first time as he stood there on the roof. "Rook?"

"Yeah?"

"You're not wearing any clothes."

Rook found Keith Tahoma where he knew he would at seven in the morning. In Union Square playing simultaneous games at a pair of Parks Department chess tables. And winning both.

Nikki watched the skinny old guy in sungla.s.ses, with the George Carlin whiskers and gray ponytail, dancing from game to game, talking smack and busting some blatantly OCD moves. Through a taut smile she muttered to Rook, "Are you kidding me?"

Even though Heat had accepted intellectually that it was time to get some expert help with the code, Rook still had to overcome her emotional reticence. "Look, you said yourself that Wynn may be trying to cover up something imminent." He tapped the copies of the marked-up music they had scanned. "We might be sitting on the answer to that right here. And the longer you delay, the greater the chance you're blowing your shot at stopping whatever conspiracy you believe is heating up. Now, if you want to be all proud and stubborn and bang your head against the wall while time slips away, go ahead. But if you seriously want to crack this, I trust my expert completely."

Rook's expert tore open six packets of sugar, dumped them all at once into his coffee, paddled-stirred the paper cup waving his pipe cleaner arms, and then sipped with a stage wink across the cafe table at Nikki. "Mr. Tahoma, I hear your grandfather was one of the Navajo code breakers back in World War Two," she said.

"You're a friend of Rook's, you call me Puzzle Man, OK? And yeah, my shi'nali was a Windtalker, d.a.m.n straight." He blew across his coffee and set it down. "He and his unit created codes for the Marines rooted in our Navajo language. Totally skunked the j.a.panese. Is it in my blood? Duh. I spent the Cold War in the army eating schnitzel and cracking signal traffic out of East Berlin, basically getting medals I can never wear for turning the Soviets into jacka.s.ses. The NSA s.n.a.t.c.hed me up, and next thing, I'm breaking down secret cables about who shot down an airliner over Korea, which tent Gadhafi sleeps in, and who's buying ammo for the Chechen rebels."

"Is that where you and Rook met, Chechnya?"

"f.u.c.k no," he said. "Star Trek convention."

Rook gave her a rueful shrug. She asked Tahoma, "I a.s.sume you're no longer involved in government work?"

"What gave me away, the shorts and flip-flops?" His high-pitched laugh turned a few heads, then he leaned in to her speaking in a low voice. "I was invited to pursue independent interests when a psychological review suggested I might be borderline." He c.o.c.ked an eye and grinned, "Like that's a drawback in the spook trade."

In a weird way, his nuttiness made it easier for Nikki to make the leap. An on-the-spot, unscientific gut profile told her that Puzzle Man possessed a genius-level knack that also made him such a social misfit that he survived by operating under strict personal rules. He was a head case who not only broke codes, he lived by one, too.

Plus, Rook had nailed it. The longer she sat on this, the more likely she was to squander the opportunity, either to find Wynn or to head off whatever he was involved with-or both. Time to give Puzzle Man his shot.

Ten minutes later, at the kitchen table of his cluttered shoe-box apartment above the Strand Book Store, where he worked part-time, Keith Tahoma swept aside the draft of the 3-D anacrostic-Sudoku puzzle book he was designing and studied the copies of Heat's coded sheet music. She tried to give him the provenance; that the pencil marks between some of the notes appeared in the songs of Nikki's old piano exercise book, and how her mother, whose handwriting this was, had been killed hiding some unknown secret information from spies. But when she began to speak, Puzzle Man just snapped a finger at her to stop, keeping his eyes riveted to the pages. After a few minutes, he looked up at the two of them and said, "Man, I am impressed. And I've seen them all, Vigenere ciphers, Polybius squares, Trimethius tableaux, Alberti discs, the Cardano grille, Enigma machines, Kryptos... I've trained in acrophony, redundancy, word breaks, Edda symbols. But this. Wow."

"What does it say?" asked Rook.

"Beats the f.u.c.k outta me." Heat's chin dropped to her chest. "But dispirit not. Give me some more time to ra.s.sle this gator."

At the door on the way out, Rook said good-bye, but Puzzle Man didn't hear. He was already lost in the code.

Nikki's first order of business when she arrived at the Two-Oh was to pull in Malcolm and Reynolds to help Rook and Rhymer set up their RFID track on Tyler Wynn. She knew Captain Irons would pitch a fit when he got a whiff of the redeployment of a.s.sets from the serial killer investigation, but the electronic consumer tracking presented the hottest lead in either case, and Detective Heat's training and experience dictated the hot lead was the lead you followed until a hotter one came along.

That happened mid-morning.

Raley and Ochoa came to her desk, each one trying to get there first. "Detectives, you've got those funny looks again," said Heat.

"I know you don't like curse words in the bull pen," said Ochoa, "but see this grin? This definitely is my s.h.i.t-eater."

Raley said, "We spent all morning over in Long Island City at Bedbug Doug's HQ. You should see the place; it actually has a giant metal sculpture of a bedbug on the roof."

"Anyway," continued his partner, "we went there to go over the victim's accounting books, like you had us do with Conklin."

"And you found a connection to one of the other victims?"