After the meeting, Petra asked him, “What does that mean?”

Mac collected his papers and didn’t look up. “What does what mean?”

“Backup.”

“I’m open to ideas.”

“The unidentified girl,” said Petra. “I’m wondering if she’s the key. No one’s reported her missing.”

“Funny, isn’t it,” said Mac.

“Maybe someone wanted her really gone.”

Mac smoothed his glossy hair. “You want to try to chase her down some more?”

“I can try.”

“Yeah, it’s a good idea.” He frowned.

“What?”

He touched the front of his flat, seamed brow. “I got a big fat what-if floating around in here. As in what if there was no motive. Just a bunch of bad guys out to kill some people.”

“Wouldn’t that be lovely,” said Petra.

“It could be, though.”

“It sure could.”

Two days of working the anonymous girl proved maddening. Petra was at her desk eating a hot dog when the sound of a throat clearing made her look up.

Isaac Gomez. Again.

He stood off to the side, wearing his usual blue button-down shirt, pressed khakis, and penny loafers. Black hair parted and plastered down like a choir boy’s. Smooth, brown face all freshly scrubbed. He held a stack of old murder books to his chest and said, “I hope I’m not bothering you, Detective Connor.”

Of course, he was. Of course, she smiled up at him.

Every time she saw Isaac, Petra thought of a Diego Rivera kid grown up. The hair straight as brush-bristle; the nutmeg skin; the huge, liquid, almond eyes; the clear hints of Indian blood in the elevated cheekbones and finely boned nose.

Isaac was five-ten, maybe one-fifty, with square shoulders, bony wrists, and a deliberate but awkward way of moving.

Chronologically, he was twenty-two.

Twenty-two and a year from his Ph.D. Lord only knew how old he was intellectually. But when conversation veered away from facts and figures, he could end up mired in aw-shucks adolescence.

Petra was sure he was a virgin.

“What’s up, Isaac?”

She expected a smile- the embarrassed smile she seemed to elicit from him. Nothing about happiness, everything about the jitters. More than once, when they were together, she’d spotted a tenting of khaki in his crotch area. The flush around the ears, the quick cover-up using a textbook or his laptop. When that happened, she pretended not to notice.

No smile this evening. He looked tense.

Eight-fourteen P.M. The detectives’ room was nearly empty, reasonable people had gone home. She’d been playing with the computer, logging on to missing kids’ databases, still trying to trace the girl in the pink shoes.

“You’re sure I’m not intruding?”

“I’m sure. What are you doing here at this hour?”

Isaac shrugged. “I got involved… started with one thing and ended with another.” He hefted the pile of blue notebooks. His eyes looked hot.

“Why don’t you put those down,” said Petra. “Pull up a chair.”

“I’m sorry if this is disruptive, Detective Connor. I know you’re working Paradiso, and under normal circumstances I wouldn’t intrude.” Flicker of smile. “I guess that’s not true. I’ve intruded quite a bit, haven’t I?”

“Not at all,” Petra lied. The truth was, babysitting Brain Boy could be a butt-aching disruption when things got busy. She motioned to a side chair and he sat.

“What’s up?”

Isaac played with a collar button. “I was working on my multiple regression analysis- plugging in new variables…” He shook his head. Hard. As if emptying it of extraneous information. “You don’t need to hear all that. The essential point is I was searching for additional ways to organize my data and, serendipitously, I came across something I thought you should see.”

He stopped. Took a breath.

She said, “What, Isaac?”

“It’s going to sound… on the surface, it may look like nothing, some kind of coincidence… but I’ve done statistical tests- several tests, each one covering the mathematical weaknesses of the others- and it’s obvious to me that it’s not just factitious, not just a quirk. As far as I can tell, this is real, Detective Connor.”

Unblemished, brown cheeks were suddenly slick with sweat.

Petra sat there.

“It’s totally weird,” he went on, suddenly sounding like a kid, “but I’m sure it’s real.”

He began flipping open murder books. Started off talking softly, at a near whisper. Ended up shooting out words, like an automatic weapon.

Assault-brain.

Petra listened. Brilliant or not, the kid was an amateur, this had to be nonsense.

As if reading her mind, he said, “I promise you, it’s genuine.”

She said, “Why don’t you tell me about those statistical tests of yours?”

Irma Gomez had been working for the Lattimores for nine years before she said anything about the problem with Isaac.

Doctors Seth and Marilyn Lattimore lived in a nineteen-room Tudor on Hudson Avenue in Hancock Park. Both Lattimores were surgeons in their sixties, he a thoracic man, she an ophthalmologist. Both were no-nonsense perfectionists, but pleasant and generous when not weighed down by professional concerns. They cared deeply for one another, had raised three children, all presently in various stages of medical training. Thursdays they played golf together because Thursday was co-ed day at the country club. In January they traveled for one week to Cabo San Lucas and every May they flew to Paris on Air France, first class, where they stayed at the same suite at the Hôtel Le Bristol and made the rounds of Michelin three-star restaurants. Back in California, every third weekend was spent at their condo in Palm Desert, where they slept in and read trashy novels and wore copious amounts of sunblock.

Six days a week, for ten years, Irma Gomez had taken the bus from her three-room apartment in the Union District and showed up at eight A.M. at the Lattimore mansion, where she let herself in through the kitchen door and disarmed the security system. She began by cleaning the entire house- the prettying-up chores, the surface work. Detailed tasks- polishing, scrubbing, serious behind-the-davenport dusting- were divided up, per Dr. Marilyn’s suggestion, because the house could be overwhelming.

Monday through Wednesday, the downstairs; Thursday through Saturday, the upstairs.

“That way,” Dr. Marilyn assured her, “you can end the week on an easier note. What with the children’s rooms being closed off.”

The “children” were twenty-four, twenty-six, and thirty, and they’d been out of the house for years.

Irma nodded assent. As it turned out, Dr. Marilyn was right, but even if she hadn’t been, Irma wouldn’t have argued.

She was a quiet woman, made quieter by her failure to learn English better during the eleven years she’d lived in the United States. She and her husband, Isaiah, had three kids of their own and by the time Irma began working for the Lattimores, Little Isaiah was four, Isaac two, and baby Joel, a rambunctious infant, active as a monkey.

At age twenty-three, Irma Flores made her way from the village of San Francisco Guajoyo in El Salvador, up through Mexico, and across the border into the United States, just east of San Diego. Prodded along in the darkness by a vicious coyote named Paz who attempted to blackmail her for more money than they’d agreed upon, then reacted to her refusal with an attempted rape.

Irma managed to free herself and, somehow, found her way to downtown L.A. To the door of the Pentecostal church where sanctuary had been promised. The pastor was a kind man. A janitor when he wasn’t preaching, he found her night-work, cleaning downtown office buildings.

Church was her solace and it was in church that she met Isaiah Gomez. His quiet demeanor and shabby clothes brought out something soft in her. His job was dying sheets of fabric in an East L.A. plant, leaning over steaming vats, inhaling toxic fumes, trudging home pale and weary in the early-morning hours.