She was gone before Carmen could answer.
Or ask what it was about the body that had made the medical examiner call for a detective, but Carmen didn’t realize that until later, when the ceiling over her bed was staring her down.
After four days, Carmen made herself stop searching for news coverage on the murder. Becoming obsessed with a slow-breaking story wouldn’t help an overworked, underpaid public servant get her job done.
Her work was tracking the progress of the mesh as it built itself—reclaimed scrap of microplastic by reclaimed scrap of microplastic—along the edge of the bay. Supporting it. Protecting people. Building habitat for animals. Regreening sequestered carbon, and that too helped the warming world weather its changes.
On the seventh day, Carmen looked up from her spreadsheets to find Quinn lounging against the doorframe, watching her.
“How’d you get in here?” Carmen blurted, aware as the words left her mouth how weird—how guilty—they made her sound.
“I’m a city employee too.” Quinn’s intent gaze never wavered, a frank inspection that left Carmen feeling awkward and self-conscious. “I came to ask your help with some forensics stuff, actually.”
“Aren’t I a suspect?”
Quinn’s head tilted. “Should you be?”
“… No? I just thought… Isn’t the person who finds the body always a suspect?”
“You’ve been watching too many CSI shows.” Quinn walked into the office, moving as easily as she spoke. She shut the door behind her, glancing at Carmen for permission. “Not when the body is a floater washed up at the soft edge, and the person who found it is an engineer performing her assigned duties. Unless you knew her, of course.”
“Has her name been released and I missed it?” Carmen called up a search bar. Her mouth twisted. She made herself close it again. I must not develop unproductive obsessions. I must not develop unproductive obsessions. I must not develop—
“Not yet,” Quinn said, following Carmen’s gesture to a chair. She sat and crossed her legs.
“Is it still not suspicious if the engineer in question is an expert on tide patterns?”
“Do you want to be a suspect?”
Carmen put the heel of her hand to her forehead and laughed ruefully. “No?”
“Then stop making the case for it.” Quinn uncrossed her legs and leaned forward, elbows on her knees, making the coat of her beautifully cut dove-colored suit flare.
Carmen lifted her chin and decided to get it out in the open. “This wouldn’t be the first time I’ve been accused of a violent crime.”
“I know,” Quinn said. “I looked you up. You were cleared.”
“Cops don’t usually care about things like that.”
Quinn smiled. “You spent six months in jail awaiting trial. I understand why you automatically hated me, now.”
Carmen decided not to dignify that with an answer and shut her half-open mouth very quietly. “Nobody should go to jail,” she said, instead.
“You and I will have to differ on that one,” Quinn said. “I’m sorry to say, this is probably a sexual homicide.”
“Sexual—” Those were not words Carmen would usually put together.
“Serial killer,” Quinn said tiredly. “Or about to become one. We need at least three bodies before we can call the FBI.”
Carmen bit her lip. She was, she knew, flailing.
“What do you know about”—Quinn looked down at her handheld—“identifying the provenance of microplastics and seawater?”
“I literally wrote the book on it.” Carmen swiveled her chair away from her computer and leaned her elbows on the blotter. Relief welled through her. This was something she knew how to deal with. Not like… sexual homicide. Not like the possibility of sending somebody else to jail.
Quinn said, “Is there anything you can do to help us catch the killer? Can you tell me based on, maybe, tide charts and trace evidence on the body where she might have gone into the water?”
“I can probably rule a lot of places out. The mesh filters microplastics and reprocesses them to manufacture more soft edge, so if there’s a lot of microplastics in her clothes, she didn’t drown near our tech perimeter.”
“I have samples extracted from the victim’s lungs,” Quinn said. “Would you look at them for me?”
“You have to understand,” Carmen said carefully, “that I am utterly opposed to prisons on an ethical and logical level. I think they’re a terrible idea that harms society and creates more crime.”
“Sure,” Quinn said, disarmingly. “You’re probably right. But that terrible solution is the best solution I know of to keeping violent habitual offenders from re-offending, and I have a degree in criminal justice. So. Will you help?”
“I shouldn’t.”
“But?”
“The science might be interesting,” Carmen said.
From Quinn’s wry expression, Carmen understood that Quinn, too, felt the inescapable urge to know and reveal the truth. The detective was also a kind of scientist, testing hypotheses and collecting data. The urge to find out was the strongest motivator of all.
Carmen sat back. “Wait. If she drowned, why did the first responders call homicide?”
“Her hands,” Quinn said levelly, “were wired together behind her back.”
Carmen breathed the worst swear she could think of. Quinn observed with interest, and nodded.
“I won’t be able to help you,” Carmen said, forcing a smile.
The samples reeked. Carmen could only assume the funk was from decomposing lung tissue. Cadaverine, putrescine. She left the vials to settle overnight, eyedroppered the dregs, centrifuged them, and separated the layers onto slides. She reclosed the vials and got the cover slips in place as fast as possible before bending over the microscope. That done, she searched databases and squinted at enlarged pollutant concentration maps until her head felt as if it were being squeezed in a vise.
At eight p.m., she drank two cups of terrible coffee with cocoa mix stirred in, instead of eating dinner. Then she started searching through the saved feeds of site monitoring stations north and west of the city. Past the soft edge, outside the current spread of the mesh. There was too much pollution in the water for the victim to have been dumped—to have been drowned—in the reclaimed area. But the mesh was growing. And where the mesh was going to be, Carmen’s colleagues had placed weather stations, and pollution stations, and all kinds of equipment to produce a picture of environmental conditions before and after remediation.
Carmen ran algorithm after algorithm, until she matched the unreclaimed plastics and pollutants in the victim’s lungs with the plastics and pollutants along a particular stretch of waterfront. There were observation stations dotted along the coast there. Some of them recorded video.
Two hours and thirteen minutes into her search, she found the footage.
She knew where the victim had gone into the water. She knew the license plate of the car that had brought the killer and the victim to that fateful place. She had some not-very-clear footage of the killer who had thrown the bound victim down an embankment into the river that must then have carried her into the sea.
A balloon drone had captured the whole thing, and saved the images into its relentless optical memory.
I can’t, she thought.
But there was that image, of the bound woman—alive, struggling—being hurled off the bank to die in the cold, muddy water below.
It wasn’t proving who the murderer might be that bothered her. It was what might happen afterward. What certainly would happen, if they were charged.