She was used to coming home and finding him in the same chair, before the glowing screen, otherworldly quacks rising from the speakers, the coffee she'd made him eight hours before drained to an inch of liquid dark as motor oil in the bluish light.

"Any theories?" she'd ask, meaning new ones, a hand against his back to acclimate him to her presence.

"Glacial shift?" he'd say, lips parting reluctantly, gummed with disuse, or "Maybe a sonar echo from a sub. There's a superhighway under that ice. People have no idea."

She knew it would take him minutes, five at least, to register the way light had shifted around him. "Seven already!" he'd say, stretching fists to the popcorn ceiling in a 'v.' She'd leave him to make a gentle ruckus in the kitchen, and before long he'd stumble in, remember to ask about her day, feign interest in the office politics she observed from a distance, like a scientist, he'd tease her. Accountants in their natural habitat, she'd say. The mating rituals alone.

But today the chair was empty. The sky had purpled and she let her shoulder bag clunk to the floor. "Darling," she called, fearing a fever or a call, the crippling kind come out of the blue to take someone away from the world. They had a daughter at Brown, not two hours away, but good as the North Pole for how often they saw her.

"Darling?" A hand at her throat. Impossible to swallow. She opened her mouth to call again, then registered the sound for the first time. A steady pounding overhead, every three seconds, roughly the same amount of time that passed between the duck-like calls originating in the Arctic that had become his obsession of the past decade. Those calls were regular enough to be manmade, but no source had yet been found. Just one grant-funded mystery to unravel among hundreds. A blessing that he could study the sounds here, both recorded and piped in live, on Cape Cod, in the home-office facing Eel Pond, or down at the Oceanographic Institute for the rare face-to-face consultation.

On the second floor, she heard the pounding still above her head. A stomping. There was no attic. Only roof. She went out the French doors to a small balcony overlooking the pond.

The quacking was just one of the mysteries that needled him awake at all hours through the second half of their marriage. She'd wake to voices whenever Margie was home. Three in the morning and the two of them sharing the last piece of apple pie, bar stools pulled up to the kitchen island. Insomnia was almost all they had in common.

Margie had excelled at math and science. They both thought she'd take up where he left off, marvel over bloom patterns of orange fungus on dying marshes, or puzzle out the shore's siren song to a sick dolphin determined to die. But she'd chosen the flute. He didn't understand. It was the one mystery he'd never hoped to crack. Such an overt rejection, unsubtle. A product of the only other thing they had in common—a stubborn streak wide as the Cape Cod Canal.

"Darling?" she called to her husband peering into the dusky blue of the day's last gasp.

His hands appeared over the edge of the clay gutter, then his face, rapturous, glowing even in the dim. "I did it," he said, gesturing her closer.

"It's late. Come down and we'll order in—"

"Minkes," he said, nonsensically. He gestured, come hither, the way he'd used to draw her into a waltz, shoes kicked to the corners, Margie kicking in the swing they used to metronome her to an open-mouthed sleep.

She took his hand. "Minkes?"

He offered direction. One foot on the lounger, another on the railing, don't look down.

On the roof, the sky was big above them, feathered with oak. The slope was gentle, shingles woven like scales to the skin of the house. They climbed to the peak.

"Minke whales," he said, one arm catching her waist, pressing her hand to his heart. They swayed, feet velcroed to the sandpaper of the shingles, roof sloping away to either side, his foot on the ridge vent, their driveway a black snake parting the lawn's green murk. "They cry every 3.1 seconds, hiding in the ice floes. Shy little rascals. Word just came back. Once they knew what to look for, the field guys got it on tape. Right beneath our noses."

Above it was black coffee, stars muffled by cloud. He helped her sidestep back to the edge, scrambled limber to balcony, guided her safely down.

"How did you know?" she asked, thinking of pizza and wine, plotting tomorrow's spreadsheets, picturing Margie bent to sheet music, nodding over each note.

He was in the shower, humming there, a distant trill. In his office, she found standing on end next to his computer the fipple to Margie's old flute, its silver coating tarnished. They bought her a new instrument last Christmas, the first time in ages they saw her struck dumb with joy, fingering all the gleaming pieces. The fipple on his desk was smudged with fingerprints, and warmed easily in her hand as if accustomed to being held fast. She ran a thumb over the oval cutout where breath entered to produce sound—a goose honk for the uninitiated. She remembered Margie's first efforts and her husband's groans. Does she have to practice that now? Now she was first chair. They saw her play in Providence last month. Reed-thin girl in a velvet dress.

It was called a blowhole, she remembered now, that place where the flautist coaxed life from steel. Last month, at the Season Finale, Margie had a solo. While a ribbon of sound spooled out from the gleaming instrument, her foot beneath a floor-length gown had tapped, tapped, tapped, tapped, almost impossible to believe she authored that sound, its trill, its cry.