In the apartment building across from the theater, the light in the far-left window of the third floor flickered on. Io tore her gaze away from the moon and put her spectacles on. Sure enough, it was the very apartment she had been hired to watch. A figure moved inside—maybe two? She slid down and grounded her palms on the splintered wood of the balcony. Before you slip into the Quilt, make sure you’re safe, Thais used to instruct. We don’t want you walking off a rooftop, do we?

Io blinked and the Quilt appeared, a jumble of threads laid over the physical world. Only moira-born, descendants of the goddesses of Fate, could see the lines of silver that sprouted from every person, connecting them to the things they loved most in the world. Io focused on the apartment on the third floor. In the Quilt, she saw beyond brick and wood, straight to the two people in the apartment. Dozens of threads emerged from their bodies, linking them to the many different places, things, and people they loved. One of the brightest threads connected the two figures together, pulsing vividly, the kind of luster that consumed everything. The singular brilliance of a love-thread, in Ava’s moonstruck words.

The singular tedium of a pain in the neck, more likely. A sigh escaped Io’s lips. Why was it always cheating? Why couldn’t it be a weird hobby or a late-night class for once, something that wouldn’t crush her clients’ souls? Io could picture it clearly: tomorrow, her client, Isidora Magnussen, would sit at the table farthest back in the café on Sage Street, her coat wrung like a dish towel in her hands, and Io would have to tell her, Yes, your husband did go to the apartment he supposedly sold three weeks ago. Yes, he had company. Then the hardest part would come: Does he love her? Any other private detective could shrug and say, How would I know?

But Io was different. Io was moira-born. It was why clients chose her; they didn’t just want to know if their loved ones were cheating or gambling or drinking. They wanted to know the secrets that only the Quilt could reveal: if their spouses loved cheating and gambling and drinking more than they loved them.

And Io would have to tell her. I’m sorry, Mrs. Magnussen. Their thread is so bright I couldn’t stand to look at it for more than two seconds. It means your husband’s in love with his mistress. It means I want to slip through a hole in the café floor and never come out. That was what put a roof over Io’s head and food on the plate: breaking people’s hearts.

She watched the two figures a while longer, just to be sure. She made out no bodies in the Quilt, only the threads, but there was no mistaking it: the couple came together, silver interweaving in a slow embrace. Io’s cheeks heated—she glanced away.

Something caught her attention. Close to the couple, on the third floor of the apartment building. It was a person, but also . . . not.

The un-person had only one thread. People loved in multitudes; they got attached to others, to places, to objects, to ideas. The average person’s thread count was fifteen. Newborn infants had the fewest: their life-thread, a thread to their mother, and a thread to food—the last two usually one and the same. This person, however, standing in what must be the apartment building hallway, had a single thread. On its own, that was improbable, but not impossible.

What was impossible was that the thread was severed. It came out of the person’s chest on one end, and the other just flopped limp to the floor, where it frayed into nothing. Threads connected—there was no such thing as a one-ended thread.

And worst of all, the severed thread was tilted at an unnatural angle, like the person was gripping it in both fists. Stretched tight and sharp, as though meant to cut someone else’s threads. This single-threaded person, this impossibility, was a cutter. Io knew, because Io was a cutter, too.

The cutter was edging toward the lovers’ apartment, their lone thread a raised weapon. Io’s shoulders tensed. Her breath caught in her lungs.

Little idiot, her sister berated in Io’s mind.

She breathed out and ran.