It was easy to hear the sound, so River let them think that's what set her off each time.

"You must be sensitive to it, like a dog whistle," one of the new guards said as she put on her lipstick. One of the stupid ones, assigned to her only when no one else was available.

"That's why you start packing hours before it shows up," he said.

"Yes," she whispered, and motioned to him through the bars. "That's it. Now come closer and I'll explain it all to you."

River had long ago started to lace the hypnotics in her lipstick with enough additional drugs to clear their minds. Even the smartest of the guards would forget any details of her escape except the sound that echoed through empty corridors. A few recalled the vague outlines of a box.

They never remembered the man who stepped out of the brightly lit doorway once the sound stopped. Or the way he glided across the floor in three fast and certain strides. The Doctor was always able to stay just out of sight, back in the shadows. And he'd stay there, as long as River could help it.

But that wonderful sound, of course, was never the first hint - not that she'd ever tell them that.

The first sign was a knot, deep inside her body, buried within her lone heart. She'd come to think of it as muscle memory, her body remembering something she thought she'd forgotten. Some reminder from all of time and space. River wondered sometimes if this was something she'd inherited from Amy, from a mother who grew up with a crack in time spilling through her bedroom wall. Or maybe this was some gift inherited from the TARDIS in the first hours of conception, cells splitting and doubling while exposed to all of space and time, telling her secrets she'd spend her life learning all over again.

Then, just before the sound came, just before the light, just before the adventure, before everything opened itself to her again, the hairs would stand up on her arms and on the nape of her neck, a shock of electricity tightening her curls.

She always made sure that guard would be silent by then, staring dumbstruck at the wall, or the rectangle of sky in her window, a sky that was always a soggy gray.

"They're going to confiscate your lipstick one of these days, you know," the Doctor said. He leaned against the open door of the TARDIS.

River pushed open the cell door with the tip of her index finger. "They have," she said. "Many times. And for some reason, they always give it back to me."

She leaned in to kiss him.

The Doctor dodged her. "Perhaps later. I never cared for that particular shade." He spun on his heel, made a circular motion with his index finger in the general vicinity of her lips. "Or chemical combination."

"That's not what you said last time." River walked past him to the console. She saw his face reflected in the dark surface of the monitor as a brief moment of confusion passed over him. She reached for the controls. "So where are we off to this time?"

He slapped her hand away. "That's a surprise."

"A surprise? Or a challenge?"

"You'd like it to be a challenge, wouldn't you?" The Doctor leaned back against the console, then pushed himself away, interrupting a brief moment of stillness. "Wait. No. It's not. Definitely not a challenge. Never mind." He looked up at the ceiling. "It's a surprise, remember? Of course you do."

He stopped lecturing the TARDIS and instead wagged his finger at River. "Just be patient."

"Spoilsport."

River listened to the engine, wondering if she could figure out their flight just by the slight variations in sound as it skirted the edge of solar systems, the slight atmospheric changes from the stars.

"So where are you coming from?" She'd triangulate if she had to. Points on a compass - where she had been and where he had been would give two specific spots to begin with.

"Earth," he said, "sort of."

"Sort of? Someone trying to change the future again by changing the past?"

"Don't they always?" He stared at her and she remembered seeing him inside his own body, in a place and time that never was. And of a wedding that may or may not have ever been. Except to her. Of course that had happened long ago, according to the notes in her journal. No telling how long it had been for him.

River sat on the chair at the edge of the deck. She crossed one leg over the other, leaned back with one elbow on the railing. "So where have you been?"

"Not telling."

"What about when?"

"Definitely not telling."

"So that's definitely a challenge."

"Not a challenge, I told you. A surprise."

"I don't like surprises," River said. "I prefer challenges."

The Doctor looked up from the console, craning his head slightly to one side as if he had to look at her from some new angle. "You got that from your mother," he said.

"How long has it been since you last saw her?" River asked.

He smiled then, the smile that always stretched across his face when he he was convinced some mad plan of his was about to work. Too clever by half.

"So let's compare notes," he said. "Byzantium. You've been there already, haven't you?"

It was the place she always started in this tradition. It was one of the places that meant the most, the time that Amy came to know her. River. The person she finally became. Not just Mels.

"Yes," she said.

"And Stonehenge?"

"Of course." Rory. The Last Centurion. He was that part of her that made her hold on, and never give up, no matter how long it took.

"What about New York?"

"Which New York? New New New New York? Or just New New York?"

"This one." She felt the change the in the TARDIS as its engines as it came to a silent landing. River wondered for a moment if he'd finally learned how to do it himself, or if it was the TARDIS' doing, its part in the surprise.

"How about a hint?"

The Doctor ran down the ramp, then skidded to a stop. "You're the archeologist," he said and he pushed open the door. "You tell me."

River stepped out and felt concrete beneath the soles of her shoes. It was warm and moist, the heat still seeping out from a summer's day. There was a yellow glow from a street lamp at the end of the block.

"It would be easier to do this in the daylight," she said.

"And where's the challenge in that?" The Doctor closed the door behind them, bounded two steps in front of her. "Come on now. Where are we?"

River was good at making out details, even in the dark. The Silence had seen to that. And Madame Kovarian, of course. Besides, the stars were as good as any street sign. "New York," she said. "The original one."

"Ah, but where, exactly?"

She looked along the street. Tan brick buildings crowded against each other. Each had six steps leading up to a wide stoop on each one. She ran her fingers along the side of the wall, felt the texture of the mortar set between each layer of bricks. Forty years old, maybe fifty.

"Harlem," she said.

"You're guessing."

"Am I wrong?"

"That's the easy part. When?"

River glanced at the people strolling past them, the coffee and cream and cocoa-colored mixture of skin tones, the men in summer wool suits, the women in light-colored dresses embellished with lace in fine, tight stitches, the cloth ending just above their ankles.

"Even easier. Nineteen twenty-two? Maybe even as late as mid-1929."

The Doctor led her around the corner where darkness was lifted by overpowered lights further down the street, strobes arcing out into the night sky.

"The Cotton Club isn't exactly low profile, is it, sweetie?"

"Maybe not, but Duke Ellington's just starting his first set as the new house band." He leaned in close to her, his hand just skimming over the back of her silk blouse. "I've just come from a wedding, and you know I always dance at weddings."

"And there wasn't a band at this wedding?"

"Nothing but a pyramid, and some odd signally device some mad woman created."

"What a shame."

He took her hand and rushed ahead of her, pausing only for the doorman to let him past the line waiting outside.

"Good evening, Doctor."

"You do realize you're supposed to be dead, right? Not running about advertising yourself to the universe."

"One advantage to time travel. No one's quite certain when you're coming from." River nearly stumbled when he came to a sudden stop. "I suppose someone should say thank you, for the prison time and such."

"Don't worry. You will." She pulled him forward now, between tables and toward the dance floor, following the sound of a sax and trumpet, piano chords creating their own slow counterpoint.

River let him take the lead as they reached the dance floor.

"Nine hundred years and nearly a dozen lifetimes," she said as he tried to twirl her around, only to tangle himself up in her arms. "You would think that somewhere along the line you would have picked up a simple box step."

"Box steps are boring." The Doctor stepped away from her, waved his hands in the air. "You know what's cool?"

"You are not dancing the Charleston," River said. "Not on our wedding night."

"Ah, but it's not that night from your perspective. It's years later. I checked," he said. "Besides, the Charleston's cool."

"I don't care." River pulled him forward by his lapels. "And it's my wedding night."

"Sort of."

"Hold on a minute. Sort of?" River took a step closer to him, ignoring the other dancers who stared at them. "I don't care which timeline you're talking about. I was there. There was a cloth. Amy and Rory were both there." She stared at him. "But you didn't tell me your name."

"I didn't."

"So -"

"At least, not yet."

"Not yet?"

The Doctor smiled that smile again. Some mad plan falling into place.

"What do you mean, not yet?"

The Doctor reached for her, one arm around her waist, pulling her close. His lips brushed against her ear. "Spoilers."