Splash! A man just jumped off the Lefty O'Doul Bridge. It was the kind of sunny April afternoon that brought nine-to-fivers along the waterfront beside AT&T Park for lunch, and they all saw it. Casey Shafer certainly saw it. "Holy shit, is this happening?" he thought to himself. He was eating soup and sandwiches with a couple of co-workers from his tech company. The dozen or so people in the area looked around at each other to make sure this spectacle was as out-of-the-ordinary as they thought. And then they began shouting encouraging words at the man — he was only about 30 yards away.

The man was struggling to stay afloat. Any theory that this man was trying to kill himself shattered when the man began stripping off his clothes, perhaps because they were weighing him down. But the man was not swimming over. Instead he yelled a stream of curse words toward the people observing him: "Fuck everyone! Fuck the world!"

People pulled out their cell phones, calling 911. The responders wouldn't arrive for minutes, though, and who knew how long this man could tread water? So Shafer jumped in.

It wasn't the instinctive reaction of a movie superhero. No; Shafer, like most reasonable folks, thought this through. "If I watch this man drown and I don't do anything about it, that's gonna mess me up for a long time," he would later recall. "I thought about how it was gonna affect me. It wasn't selfless."

He was a fairly good swimmer. He figured he could pull the guy onto his shoulder and backstroke them to safety.

The water was colder than he thought, the current stronger. Still, he reached the man in less than a minute. He held out his hand. The man grabbed him and pulled him under water. Perhaps the man was panicking, flailing. He was a big man, around 6-2, much larger than Shafer's 145-pound frame.

Shafer popped up for air after three or four seconds. And when he did, the man looked him in the eyes and screamed, "I'm going to kill you!" The man pushed Shafer's head under water once more. Now it was Shafer who was in trouble. This was no longer a rescue mission, but a survival mission. Confused, scared, and about to drown, Shafer kicked the man off him, and summoned every bit of energy out of his tired body to swim away. The man chased. Shafer pumped harder. He could hear shouts of concern from the waterfront, and he swam toward the noise.

In a few minutes he would be in his underwear wrapped in a fire department blanket watching police officers in wetsuits carry the man out of the water and onto a gurney before taking him to Mental Health Detention at San Francisco General Hospital. In a few hours he would be back at his office, recounting the tale to co-workers and wondering whether "that piece of me that would do something like that, that I didn't even know existed, whether that piece of me was damaged." In a few days, he would be outraged to learn that the man who tried to kill him would face no criminal charges and could be released to the public as soon as the hospital believed he was fit.

But right now, Shafer was focused on climbing out of the water, onto the comfort of land. The crowd of spectators was bigger now than when he had left it. As Shafer stood there dripping, he saw one of them pulling boots back onto his feet. The guy looked at Shafer and said, "I was just about to go in and save you."