A few weeks after the discovery, they're gathered in California to surprise King on his birthday.

A blast shatters the night

For sailors aboard the USS Indianapolis, it all began with promises of romance and adventure.

"Join the Navy and see the world!" the posters lining telephone poles read. "A girl in every port," they promised. Harold Bray had half a year left in high school when he persuaded his father to let him sign up for the Navy.

"When I went in, I had no idea or reason to believe that anything would ever happen to me," Bray told CNN.

He boarded the USS Indianapolis while it was under repair at Mare Island in California, a bustling naval base that boasted as many as 50,000 workers during WWII. They could fix anything at Mare Island, including a heavy cruiser recently slammed by a suicide plane. Three months in their skilled hands and the ship looked as good as new, Bray said.

Just after midnight on July 30, midway through its course, torpedoes blasted out of a Japanese submarine and ripped into the starboard side of the USS Indianapolis. Survivors have said they knew, at that instant, their ship was doomed.

A hellish wait for rescue

Chaos erupted, survivors have recalled. Men shrieked as they burned alive in the aftermath of a fuel tank explosion. Then came the deafening growl of the rolling ship.

Dawn broke. Hours passed. The sun set, but still no one came.

The reason remains under debate. The Navy claimed a distress signal was never transmitted, though a radioman aboard the ship swears it was. Other communication failures meant officials didn't notice when the ship didn't arrive in the Philippines. Some believe intelligence agents decoded a Japanese message reporting a sunken American battleship but considered it a trap.

For five nights and four days, the American sailors floated in the South Pacific with no food and no water. Because the ship moved forward as it sank, they were spread over miles, small groups not knowing each other's fate.

Survivors have said anyone who'd been badly hurt in the attack didn't last very long in the water. They succumbed to injuries or to the sharks, which circled beneath the crystal-clear water by day and glided past survivors' legs at night.

Those with open wounds or white clothing seemed to be at highest risk of a shark attack, Bray recalled, along with those who ventured off on their own. Some sailors couldn't stop themselves from guzzling saltwater; they swam off toward the imaginary islands their poisoned brains had concocted on the horizon.

Of the 900 or so men who made it off the ship alive, only about a third survived to meet the rescue ships that finally arrived on their fifth night adrift. Survivors told the documentary filmmakers stories like this: There were 44 in our group; only 14 made it. We had 123 in our group; only 60 survived.

"War is a terrible thing," Bray said in a simple distillation of the hellish experience. "The only ones that suffer are the young people, the kids that have to go and fight these things."

A war hero returns, only to vanish

King never dwelled on his time in the water, he says. He preferred to remember instead the homecoming: the big parade that awaited them in San Diego, with girls running alongside their buses and handing them beers. He left the Navy and earned a master's degree in psychology. He married a Catholic girl who died too soon. He traveled the Middle East between visits to his nieces and nephews.

"My uncle was very protective of me growing up because I was the only girl in a whole group of boys," Shirley Ezel told CNN.

King would visit her family in Michigan to help out while their dad was out of town. He once bought 12-year-old Shirley a brand-new dress to wear to an ice cream social at school.

"I felt like a million bucks that day," she said. "It has stayed with me my whole life."

King usually wrote home two or three times a year, said his nephew, James "Dale" Bogard. Then in the early 1980s, the letters stopped. Bogard's mother tried for years to find him, as did Ezel.

"Honestly, no one really knows what happened," Ezel's son, Ryan Summers, said. "My father dropped him off at the airport, and that is the last time anybody in the immediate family knew of his whereabouts."

A ship is discovered and a family reunited

Through the years King's family searched for its war hero, other relatives and comrades of those aboard the USS Indianapolis mourned all that was lost with the ship. Even as the decades passed, some pledged not to allow the remains of the grand vessel to linger, lost at sea.

"That was a great day," Bray said, chalking it up as one of his happiest. As chairman in recent years of the USS Indianapolis Survivors' Organization, Bray had met fellow sailors -- including some, like King, whom he didn't know during the war -- and he hoped they and the families of the fallen would finally find some closure.

"Now the people that lost 880 kids know where they are," he said.

News of the ship's discovery also kindled a spark in Summers, King's great-nephew. A history buff, he'd always known the warship story. Now, an online search led him to Bray's survivors' group's website. An article caught his attention.

It mentioned that for the first time, the number of living USS Indianapolis survivors had risen, from 21 to 22. The name that had been moved from "deceased" to "living" on the membership list? "A.C." Tony King.

Summers rushed to tell his mother, who posted a message to Bray's group. Within hours, she got one back. That night, she spent 45 minutes on the phone, talking with the uncle she believed she'd lost forever.

"The only thing we could say was, 'I can't believe it's you. I can't believe that you're really here,'" Ezel said. "If the ship had not been found, this may not ever have happened."

A few weeks later, CNN helped unite Ezel, Bogard, Summers and Bray in California for King's 92nd birthday. They surprised King at the Mare Island Museum, a sprawling brick building with a 15-foot iron anchor outside the front door. (You can watch their tearful reunion in the video atop this story.)

As Bray and King sat side by side in their wheelchairs, they discussed what many old men must: their health, pensions and the mess younger generations have made of the world.

After a while, Bray stood up. He reached into his back pocket and pulled out a medallion that he placed in King's hand. On the back was the outline of the USS Indianapolis, the ship's 10 battle stars, and a date: July 30, 1945.