“Last week, Bree and I had to haul this gear up a rickety ladder to get to a death scene. It was up on the roof.”

“Well, tonight, ladies,” says Mac, “I’m here to assist you.” His gallant offer seems to impress neither Amber nor Bree, who respond with polite millennial smiles. Except for Mac, it is an all-woman team working the crime scene tonight, a sign of feminist progress that Frankie never imagined when she joined Boston PD over thirty years ago. It delights her to see so many young women like these two now patrolling city streets or arguing cases in the courtroom or gamely lugging heavy camera gear to crime scenes. Time and again, Frankie has told her twins that girls can do anything they put their minds to, as long as they work hard and stay focused and don’t let boys distract them.

Someday, maybe they’ll listen.

When they reach the fifth floor, Amber and Bree hoist up the two heaviest boxes of gear and carry them out of the elevator, leaving Mac to carry the lightest box.

He sighs. “I feel more obsolete every day.”

“We’re taking over the world,” says Frankie. “Get used to it.”

They all pause in the hallway to pull on latex gloves and shoe covers before stepping into Taryn Moore’s apartment. Since Frankie’s previous visit, nothing has been removed, and the Medea textbook is still lying on the kitchen counter where she last saw it, the woman’s wrathful face glaring from the front cover.

Bree sets down her Igloo container of chemicals and surveys the room. “We’ll start in here. But before I mix the luminol, let’s give the place a once-over with the CrimeScope.” She points to the box Mac has just set down. “The goggles are in there. You might want to put on a pair.”

While Amber and Bree set up the camera and tripod, Frankie pulls on goggles to protect her eyes against any damaging wavelengths of light from the CrimeScope, which will be used for the initial survey of the room. While the CrimeScope will not detect occult blood, it will reveal fibers and stains that might warrant closer inspection.

Amber closes the drapes against the city glow and says, “Can you kill the lights, Detective MacClellan?”

Mac flips the wall switch.

In the abrupt darkness, Frankie can barely make out the silhouettes of the two young women who stand near the window. The CrimeScope’s blue light comes on, and Amber sweeps the beam across the floor, revealing an eerie new landscape where hairs and fibers now glow.

“Looks like your victim wasn’t much of a housekeeper,” Amber observes.

“She was a college student,” says Mac.

“This place hasn’t been vacuumed in a while. I see a lot of dust and hair strands. Did she have long hair?”

“Shoulder length.”

“Then these hairs probably belong to her.”

The blue light skims toward the coffee table, illuminating a landscape of detritus shed by the apartment’s now-deceased occupant. Long after Taryn’s belongings are removed, after her body is laid to rest in a grave, traces of her presence will still linger in these rooms.

The CrimeScope beam zigzags across an area rug and up the back of the sofa, where it comes to an abrupt stop. “Hello,” says Amber. “This looks interesting.”

“What is it?” asks Frankie.

“Something’s fluorescing on the fabric.”

Frankie moves closer and stares at a glowing patch that seems to float untethered in the darkness. “It’s not blood?”

“No, but it could be a body fluid. We’ll test it for acid phosphatase and swab for DNA.”

“You’re thinking semen? Her vaginal and rectal swabs showed no evidence of recent sexual activity.”

“This stain could be weeks, even months old.”

“Hmmm. Semen on the back of the sofa?” says Mac.

“We’re talking college kids, Detective,” says Amber. “We can give you a long list of all the weird places we’ve found semen stains. And if you think about it, if a couple does it while they’re standing up, the stain would hit the sofa right about at this height.”

Frankie doesn’t want to think about it. She doesn’t want to think about girls her daughters’ age having sex in any position. “Can we move on to the luminol?” she asks. “I’m more interested in finding blood.”

“Detective MacClellan, can you turn on the lights?”

Mac flips the wall switch. Where the patch once glowed, Frankie sees only dull green upholstery fabric. Whatever fluoresced under the CrimeScope is now no longer visible, yet she knows it’s still there, waiting to reveal its secrets.

Bree opens the Igloo container and pulls out the bottles of chemicals that she’ll combine to make luminol. Since luminol rapidly degrades, it must be mixed on the spot. “You might want to put on your respirators now,” Bree says as she pours the components into a jar and gives it a shake. “And once we kill the lights, Detectives, stay right where you are so I won’t bump into you in the dark. Okay, everyone ready?”

Frankie pulls on a respirator, and Mac flips the wall switch, once again plunging the room into darkness. Frankie hears the soft hiss of the spray bottle as Bree mists the room. Chemiluminescence has always seemed like dark magic to Frankie, but she knows it is merely the chemical reaction of luminol with the iron in hemoglobin. Long after blood is spilled, even if it is wiped away and painted over, its molecular traces will remain, silently waiting to tell a story.

As the misted luminol settles onto the floor, the true story of Taryn Moore’s death is revealed.

“Holy shit,” says Mac.

Parallel lines light up at their feet like phantom railroad tracks, marking where blood has seeped into the cracks between the scuffed floorboards, beyond the reach of any mop or sponge. What was invisible under bright light now glows with the ghostly echoes of violence.

There it is. There’s the proof.

“You recording this, Amber?” says Bree.

“Got it all on camera. Keep spraying.”

The bottle hisses again. More parallel floorboard lines appear, like railroad tracks stretching across a black plain.

“I see a drag mark here,” Bree says. “Looks like the victim was pulled in the direction of the balcony.”

“I see it,” says Frankie. “Trace it backward. Where do the drag marks begin?”

Another hiss of the spray bottle. Suddenly a wedge of fluorescence glows on a corner of the coffee table. The surrounding floor lights up with scattered bright pinpoints, like a starburst that slowly fades into a black periphery.

“Here,” Bree says softly. “This is the spot where it happened.”

Mac turns on the room lights, and Frankie stares down at where, only seconds before, splatters glowed like stars. All she sees now is the floor and an utterly ordinary coffee table, from which all visible evidence of violence has been washed away. Luminol has revealed the apartment’s secrets, and now when Frankie gazes around the room, she can picture how it all played out. She sees Taryn Moore opening the door to her visitor. Perhaps the girl does not yet sense danger when she allows her killer to enter. Perhaps she even offers the visitor a glass of wine or a bite of the macaroni and cheese she is heating up in the microwave. Perhaps she never sees the attack coming.

But then it happens: a shove or a blow, sending the girl falling against the sharp corner of the coffee table. The impact fractures her skull and splatters blood on the floor. Now the killer drags the stunned girl toward the balcony. There he opens the door, letting in a rush of cold air, a scattering of rain. Is Taryn still alive as he lifts her over the railing, as he drops her from the balcony? Is she alive as her body plummets through the darkness?

The killer now sets to work erasing the evidence of what happened. He wipes the blood from the floor and the coffee table. He stuffs the stained rags or paper towels into a black trash bag. He leaves the balcony door wide open and the lights on, carries the bag out of the building, and vanishes into the night. He gambles that no one will look beyond what appears to be a suicide, that no one will take the time to search for any microscopic traces of blood that he could not erase.

But the killer made a mistake: he also took the girl’s cell phone and probably destroyed it so it cannot be tracked. It is a small detail, one that might be easily ignored by investigators. After all, it’s so much simpler for police to close this case and move on. That’s what the killer is counting on: a cop who is too overworked or careless to consider all the possibilities or to follow up on each and every clue.

He doesn’t know me.

BEFORE

CHAPTER 19

JACK

For a week, Taryn did not show up for class, nor did she respond to any of Jack’s emails. Had she fallen ill? Returned home to Maine? Even Cody Atwood could not—or would not—tell him what had happened to her, and Jack was concerned enough to look up her Facebook page, hoping to find an update on her status, but she’d added no new posts in over a week.

By Monday, he was ready to call the school registrar and suggest a welfare check. So he was relieved when he heard a knock on his door that morning and looked up to see Taryn standing in the office doorway.