As he turned right and stopped for the light, he saw the Starbucks people out on the sidewalk, passing out bags of food and cups of coffee to the cars in front of him. Frank opened his window as one of them approached, and the employee passed in a bag of pastries, then handed him a paper cup of coffee.

“Thanks!” Frank shouted. “You guys should take over emergency services!”

“We already did. You go and get yourself out of here.” She waved him on.

Frank drove east toward the river, laughing as he downed the pastry. Like everyone else still on the road, he plowed through the water at about five miles an hour. Fire trucks passed through at a faster clip, leaving big wakes.

As he crossed one intersection Frank spotted a trio of men ducking behind a building, carrying something. Could there be looters? Would anyone really do it? How sad to think that there were people so stuck in always defect mode that they couldn’t get out of it, even when a chance came for everything to change. What a waste of an opportunity!

Eventually he came to a roadblock and parked, following the directions of a man in an orange vest. It was a moment of hard rain. In the distance he could see people passing sandbags down a line, just to the east of the U.S. Marines’ Memorial. He hustled over to join them.

From where he worked he could often see the Potomac, pouring down the Boundary Channel between the mainland and Columbia Island, tearing away the bridges and the marinas and threatening the low-lying parts of Arlington National Cemetery. Hundreds or perhaps even thousands of people were working around him, carrying small sandbags that looked like fifty-pound cement bags, and no doubt were about that heavy. Some big guys were lifting them off truck beds and passing them to people who passed them down lines, or carried them over shoulders, to near or far sections of a sandbag wall under the Virginia end of Memorial Bridge, where firemen were directing construction.

The noise of the river and the rain together made it hard to hear. People shouted to one another, sharing instructions and news. The airport was drowned, old Alexandria flooded, the Anacostia Valley filled for miles. The Mall a lake, of course.

Frank nodded at anything said his way, not bothering to understand, and worked like a dervish. It was very satisfying. He felt deeply happy, and looking around he could see that everyone else was happy too. That’s what happens, he thought, watching people carry limp sandbags like coolies out of an old Chinese painting. It takes something like this to free people to be always generous.

Late in the day he stood on their sandbag wall. It gave him a good view over the flood. The wind had died down, but the rain was falling almost as hard as ever. In some moments it seemed there was more water in the air than air.

His team had been given a break by a sudden end to the supply of sandbags. His back was stiff, and he stretched himself in circles, like the trunks of the trees had been doing all day. The wind had shifted frequently, and had included short hard blasts from the west or north, vicious slaps like microbursting downdrafts. But now there was some kind of aerial truce.

Then the rain too relented. It became a very light drizzle. Over the foamy water in the Boundary Channel he could now see far across the Potomac proper: a swirling brown plate, sheeting as far as he could see to the east. The Washington Monument was a dim obelisk on a watery horizon. The Lincoln Memorial and Kennedy Center were both islands in the stream. Black clouds formed a low ceiling above them, and between the two, water and cloud, he could feel the air being smashed this way and that. Despite the disorderly gusts he was still warm from his exertions, wet but warm, with only his hands and ears slightly nipped by the wind. He stood there flexing his spine, feeling the tired muscles of his lower back.

A powerboat growled slowly up the Boundary Channel below them. Frank watched it pass, wondering how shallow its draft was; it was twenty-five or maybe even thirty feet long, a rescue boat like a sleek cabin cruiser, hull painted a shade of green that made it almost invisible. The illuminated cockpit shed its light on a person standing upright at the stern, looking like one of the weird sisters in the movie Don’t Look Now.

This person looked over at the sandbag levee, and Frank saw that it was the woman from the elevator in Bethesda. Shocked, he put his hands to his mouth and shouted, “HEY!” as loud as he could, emptying his lungs all at once.

No sign in the roar of flood and rain that she had heard him. Nor did she appear to see him waving. As the boat began to disappear around a bend in the channel, Frank spotted white lettering on its stern GCX88A then it was gone. Its wake had already splashed the side of the levee and roiled away.

Frank pulled his phone out of his windbreaker pocket, shoved it in his ear, then tapped the button for NSF’s climate office. Luckily it was Kenzo who picked up. “Kenzo, it’s Frank listen, write down this sequence, it’s very important, please? GCX88A, have you got that? Read it back. GCX88A. Great. Great. Wow. Okay, listen Kenzo, that’s a boat’s number, it was on the stern of a powerboat about twenty-six feet long. I couldn’t tell if it was public or private, I suspect public, but I need to know whose it is. Can you find that out for me? I’m out in the rain and can’t see my phonepad well enough to Google it.”

“I can try,” Kenzo said. “Here, let me…well, it looks like the boat belongs to the marina on Roosevelt Island.”

“That would make sense. Is there a phone number for it?”

“Let’s see that should be in the Coast Guard records. Wait, they’re not open files. Hold a minute, please.”

Kenzo loved these little problems. Frank waited, trying not to hold his breath. Another instinctive act. As he waited he tried to etch the woman’s face again on his mind, thinking he might be able to get a portrait program to draw something like what he was remembering. She had looked serious and remote, like one of the Fates.

“Yeah, Frank, here it is. Do you want me to call it and pass you along?”

“Yes please, but write it down for me too.”

“Okay, I’ll pass you over and get off. I have to get back to it here.”

“Thanks Kenzo, thanks a lot.”

Frank listened, sticking a finger in his other ear. There was a pause, a ring. The ring had a rapid pulse and an insistent edge, as if it were designed to compete with the sounds of an inboard engine on a boat. Three rings, four, five; if an answering machine message came on, what would he say?

“Hello?”

It was her voice.

“Hello?” she said again.

He had to say something or she would hang up.

“Hi,” he said. “Hi, this is me.”

There was a static-filled silence.

“We were stuck in that elevator together in Bethesda.”

“Oh my God.”

Another silence. Frank let her assimilate it. He had no idea what to say. It seemed like the ball was in her court, and yet as the silence went on, a fear grew in him.

“Don’t hang up,” he said, surprising himself. “I just saw your boat go by, I’m here on the levee at the back of the Davis Highway. I called information and got your boat’s number. I know you didn’t want I mean, I tried to find you afterward, but I couldn’t, and I could tell that you didn’t that you didn’t want to be found. So I figured I would leave it at that, I really did.”

He could hear himself lying and added hastily, “I didn’t want to, but I didn’t see what else I could do. So when I saw you just now, I called a friend who got me the boat’s number. I mean how could I not, when I saw you like that.”

“I know,” she said.

He breathed in. He felt himself filling up, his back straightening. Something in the way she said “I know” brought it all back again. The way she had made it a bond between them.