His cousin's friend would have to wait.

Ellis followed the streets through the subdivision. He turned a corner, and saw Friendswood Healthcare Center, a nursing home. A line of boats had pulled up. And a line of patients sat out front, waist deep in water. Workers were lifting them, one by one, into the boats.

The two dropped the 16-foot aluminum jon boat in near Clear Creek in Friendswood, across town. The water was eight feet deep in the neighborhood. In places, they motored over cars. Dozens of other boaters were helping pull people from homes, mirroring scenes across the region.

Ellis, a 32-year-old mechanic, wasn't going to let his cousin take the boat. He grabbed his boots and waders, hugged his daughters and kissed his wife goodbye.

Erick Ellis looked at his phone. His cousin was texting him. "Is the boat running?" he asked. Ellis' cousin wanted to pick up a friend stuck in high water near Pearland, 20 miles south of Houston, where waters were rising fast, and rain still pouring down.

The bag shifted, and the oxygen keys clanged against each other.

James slipped, and the tank dipped into the water. She scrambled to readjust Harper so she didn't fall in too. The girl squirmed.

James would take Harper across first, she decided. She slung a case with her oxygen tank over her shoulder, then propped Harper on her hip. She stepped gingerly down the sloping driveway, her 5-foot-5-inch body going deeper. The brown torrent smelled like a sewer. A city-issued trash can and tree branches rushed by. Rain poured as Harper winced and tried to climb up James' shoulders, scratching her lip.

Her neighbors had assumed she'd left the day before with her friend. After the call, one of them slogged across the flooded street with big plastic bins for her medical equipment.

James' mind flashed to a business card that came with the belated housewarming cake. The card was still on the kitchen counter. She grabbed it and dialed the number.

Then she pulled it together, changed Harper's diaper, put on long pants. Got ready to leave. But how?

She made panicked phone calls. Texts. Another Facebook post. What should I have done different, she asked herself.

"Is there anyone in the med center that can help us?" she posted online. "Water levels are rising. Harper and I are safe but want to remain that way."

At 6:24, when she got up again, water wasn't just pooled in the street; it was rolling, like a river. Her house was in the bayou.

A Washington D.C. transplant, she figured it was just a bad storm, and the runoff would drain. She tried a few calls and texts, but no one answered. Then she lay down with Harper and dozed.

Ajshay James woke at 3 a.m. and flicked on a flashlight. Water covered the grass out front.

The mother

The power went out around noon. Ajshay James and her daughter had made it to a second house, of a couple they didn't know, aboard a volunteer's boat. Another family, a grandmother and her teenage grandson, joined them. Their phones blew up with calls and messages from all over Houston, India, Ohio. The batteries were draining. Reluctantly, she turned hers off.

Harper was the size of a cell phone when she was born two years ago. Doctors discovered 11 fibroid tumors; James, 23 weeks into her pregnancy, bled dangerously. The baby was deemed a "micro-preemie;" she weighed as much as a can of soup.

James named her after the 92nd Psalm: "Show forth thy loving kindness in the morning ... upon the harp with a solemn sound."

Doctors gave her a 25 percent chance to live. She finally left the hospital at 7 months.

This was to be her year of firsts. First Astros game. First fully decorated nursery. First dances with mommy. First trip to the zoo.

Now, with helicopters buzzing overhead, by the light of a candle lit at the far end of a stranger's living room, James surveyed the oxygen tanks.

One, it turned out, was empty to start with. Another had slipped into the water.

She did the math: Just 16 hours left.

The good Samaritan

Erick Ellis steered into the line of boats at the flooded nursing home. It was hard to keep steady against the current of Mary's Creek. He spun the boat once, maybe twice, then slung a rope around a lamp post. His cousin jumped out and held on.

At the front of the home, emergency workers and men in street clothes lifted patients into boats, wheelchairs and all. They hoisted a woman in a floral muumuu and hospital socks - the ones with grippy soles - into Ellis's boat.

Ellis tried to make small talk with the woman, ask her how she was. She didn't respond. They dropped her off on high ground and came back. One of the emergency workers there turned them around: Waters had trapped another elderly woman in a brick house in the neighborhood. They went looking.

But before they got far, a man flagged them down to rescue a disabled couple.

Every time they picked up one flood victim, another appeared: A man with oxygen tanks, along with his nightgown-wearing wife and their three lapdogs. A family of eight as the flood closed in on a high point in the street.

Ellis was motoring back to dry ground - they needed gas - when he looked into a stand of oak trees. He saw something floating, and almost ignored it. Then it moved. He swung the boat around.

A man, his nose and mouth barely above water, holding his wallet and cellphone overhead, bobbed in the current. He grabbed the bow, and hung on. Ellis' cousin jumped out and helped him in.

"Have you rescued a lady with a white dog?" he asked. Ellis shook his head.

The man kept describing the woman, and the dog, their whole way back to dry ground.

As if, maybe, if he could only describe her better, it would change their answer.

The mother

In a two-story house at the front of James' neighborhood, her Indian-American hosts made an early lunch of flatbread and chicken for their unexpected guests. James kept looking back at the draining air tanks.

Fourteen hours left.

Harper played with everyone, giggling and babbling with a dimpled smile.

Twelve hours.

James hid a flashlight and they made a game out of hunting for it.

Ten.

A news helicopter flew overhead, and they all waved at it.

Seven.

The gray sky faded to black.

The weatherman

As darkness fell, nearly every river, bayou and stream in the region had reached or topped its banks.

Eric Berger hunched over his computer and pounded out another update. By then, his little website was drawing more than 1 million pageviews a day from people desperate for information. Desperate for better news. A glimmer of hope.

He couldn't give it to them.

"It is anything but hyperbole to say this is the most catastrophic flooding event in the city of Houston's history," he wrote, hours after the Army Corps of Engineers announced they planned to begin releasing water from Addicks and Barker reservoirs.

The move would save the dams and prevent even more widespread destruction, but would likely fill dozens of homes with water for as long as two months.

"Truly," Berger wrote, "we don't know what happens next."

The mother

Ajshay James had never seen a night like this, almost perfectly dark while the rain pounded the roof and splashed in sheets across the black river outside.

It was about 9 p.m. when two head lamps appeared over the water. In the distance, a red flash.

The firefighters came in two boats, one for the medical equipment, the other for Harper and the strangers sheltering with her.

On dry land, four firefighters, a grandmother and grandson, James, Harper and a bin of oxygen tanks, mostly empty, crowded into a fire truck. Even amid crisis, James imagined the bill that would come if they ditched the tanks, worth hundreds of dollars, and how much worse off they'd be for it.

She looked around the cab. Was something missing?

On the truck's radio, a voice said that Texas Children's Hospital was inaccessible.

Then it hit her: She didn't have the bag with Harper's care bible and medicine. If anything happened to James, it was the only clue a first responder would have on how to keep her daughter alive.

The rescuers searched, in the truck, the boats. Splashing, yelling. Is it this bag? That bag? Fifteen minutes went by.

Someone radioed that this was to be the last truck out of the neighborhood. Water was still rising.

A firefighter held a bag up in the distance. Yes, that was the one.

The truck barged up Stella Link and onto a ramp at the 610 south loop. James' stomach lurched with every dip of the road as she watched the front bumper slice through water. It reminded her of the Red Sea.

Trapped cars dotted the flooded highway. The rescuers took James and Harper, shivering in towels, to an ambulance. James cradled the girl, looking for signs of seizure.

The ambulance coursed through the water toward Park Plaza Hospital, six miles away.

Another voice on the radio: They couldn't get there, either.

Maybe if they tried Almeda, the medics said.

Somewhere on Highway 288, they hydroplaned. James looked out the back window, saw water everywhere. The ambulance pulled over a curb and backed out.

They were a few hundred feet from the largest medical center in the world, home to some of the best pediatric specialists in the country. They could see the hospital.

And they were turning back.