“Come on, where’s your sense of adventure?” Jess began to jog toward the fence.

Ellie still couldn’t figure out how her brother-with his lifestyle-managed these runs, at this pace, with such apparent ease. She stayed in good shape with kickboxing and weight training, but serious running like this had always winded her. Anyone looking to resolve the nature-versus-nurture debate need only look to Ellie and Jess. Their lung capacities were just two of the many differences between them.

“If I stop, you may very well have to carry me home,” she panted.

“You weigh too much for that,” Jess called out, sticking out his tongue as he ran backward. “Come on. What could be good enough to get the attention of a group of New Yorkers?”

As they approached the three runners, she could see that the men’s expressions were anxious. The one with the fanny pack flipped his phone shut.

“They’re on the way,” he announced.

A wave of relief washed over the runners’ faces. Ellie had seen the phenomenon countless times when she’d arrived in uniform to a crime scene, NYPD badge in hand.

Jess had wondered what could distract New Yorkers from their routine, and she had a bad feeling about the answer. She tried to tell herself it might only be vandalism, maybe a bum seeking a temporary camping zone.

“Something worth seeing here?” she asked.

“You might not want to look,” one of the men said.

Ellie readied herself for the worst, but she could not have anticipated the scene she encountered as the runners stepped aside. A section of wire had fallen slack between two metal braces that had been knocked to the ground, leaving a substantial gap in the perimeter around the construction site.

The woman-she was just a girl, really-was propped like a rag doll against a pile of white PVC pipes, arms at her sides, legs splayed in front of her. Her sleeveless red top had been unbuttoned, exposing a black satin push-up bra and matching panties. Her legs were bare. High-heeled gold sandals dangled from her feet, but whatever other clothes had covered the lower half of her body were gone.

It was the rage behind the violence that struck Ellie immediately. She had seen her fair share of murder scenes, but had never come across this kind of brutality. The girl’s wavy hair had been hacked off in handfuls, leaving large portions of her scalp exposed. Her body and face had been crosshatched with short, deep stab wounds resembling the outlines of a tic-tac-toe game. Ellie winced as she imagined the terror that must have come at the first sight of the blade.

She heard one of the men say that they had been unable to find a pulse, but Ellie had already concluded there was no point in checking. She forced herself to focus on the clinical facts she would need for her report.

A chain of ligature marks blossomed around the girl’s neck like purple delphinium. Her eyes were bulging, and her swollen tongue extended between lips caked with dried saliva and bile. Rigor mortis had not yet set in, but the girl’s skin-no doubt vibrant and pearly just a few hours earlier-was now gray and entering a deeper stage of lividity, particularly in the body’s lower extremities. Lumps of red blood cells had formed boxcars in her retinas.

As gruesome as the mutilation had been, it had also been gratuitous. It was the strangling that most likely claimed her life.

The jingling that Ellie had noted earlier was louder now. It was coming from somewhere near the body.

She was startled by a retching sound behind her. She turned to see Jess doubled over next to a black tarp draped across a fence post, just as she became aware of sirens sounding in the distance.

“May I?” she asked the jogger, reaching for his cell phone. Punching in a number she had memorized surprisingly quickly, she led the joggers away from what would soon be marked as a crime scene.

By the time she hung up, the first car of uniform officers had arrived.

THE JINGLING TURNED OUT to be a Gwen Stefani ring tone on the dead girl’s cell phone. The alarm had been set to go off at 5:32 a.m. Thirty-two minutes after Ellie woke up. One hour and twenty-eight minutes before she was due at the Thirteenth Precinct.

What had been the significance of that specific moment to this unnamed girl? It could have been her preferred time to get up on a Monday morning. Or maybe it was a reminder to go home on Sunday night. Time to take her medications, or walk her dog. Whatever the alarm’s original purpose, by 5:32 a.m., the girl was dead, and the sound’s only effect had been to draw the attention of three passing joggers to her corpse.

It would take Ellie’s partner at least twenty minutes to reach the scene from his apartment in Brooklyn Heights. For now, she had to make sure his trip would not be wasted.

The uniform officer riding in the passenger seat exited the sector car first. He looked like a lot of new cops. Fit. Baby-faced. Enthusiastic. Short haired. Maybe in a different decade, he would have enlisted in the army. These days, he probably had a mother who stopped him. Now he was law enforcement.

He directed a flashlight at the dead girl. Ellie could tell from his reaction that this was his first body.

“Oh, Jesus.” He reached for his stomach on reflex.

“All upchuckers, over there.” Ellie directed the officer’s attention to Jess, who, as instructed, was standing well east of the crime scene, looking out at the river, taking deep breaths. “Detective Hatcher, Manhattan South homicide. I need your radio.”

Ellie had wrapped up one week in the homicide bureau, and so far all she’d done was help her new partner tie together loose ends on his old cases and play support for other teams while she supposedly “learned the ropes.” Now she’d practically stumbled over this poor girl’s body inside the Manhattan South borough. She was the first cop on the scene, and she was a homicide detective. If she couldn’t weasel her way onto this case, she didn’t deserve her new assignment.

The uniform looked at her, blinking rapidly. First a disfigured body, now a sweaty woman in a Pretenders T-shirt and sweatpants, demanding his radio.

“But-”

The young officer’s partner found the words he’d apparently been searching for once she’d stepped from the driver’s side of the car. “I’ll confirm it,” she said, reaching for the Vertex radio microphone clipped to the shoulder of her navy blue uniform. “And no one’s taking our radios. Sorry, ma’am.”

Ellie nodded. The woman was a good cop. Depending on what precincts she’d been working, this could easily be her first body as well, but she was cool. Cooler than her partner. Just a quick glance at the body, then a more careful monitoring of everyone at the scene. Three runners, pacing. The sweaty woman who wanted their radio. The tall guy, looking out of place by the water.

“Make sure that guy’s not going anywhere,” she said to her partner. She was definitely good. Of the people at the scene, Jess was the one who should have registered on a cop’s radar. And asking her partner to keep Jess company gave the obviously nervous young cop some distance from the body.

“You’re right,” Ellie said, holding up her palms. “Call it in. But tell them homicide’s already here. Shield 27990. Hatcher. They’ll have me down as Elsa.”

She listened as the officer radioed in the essentials. They were at East River Park, south of Houston, north of the tennis courts. They had a 10-29-1.

It was standard 10 code. A 10-29-1: 29 for a past crime, 1 for a homicide. Across the country, 10-codes were dying out in favor of so-called plain language. The Department of Homeland Security had gone so far as to force the NYPD to train its officers in the kind of plain English that was supposed to assist interagency communications in an emergency. Instead, the entire notion of an eight-hour training session on plain talk became just another opportunity for the NYPD to mock the feds.