Batkid, five, dazzles San Francisco
A five-year-old boy who has battled leukaemia for years fulfilled his wish to be his favourite superhero - taking on foe after foe around San Francisco dressed in a black Batman costume.
In the process, Miles Scott became a darling of social media and attracted thousands of fans around the US, including the White House.
"When you have an illness, it's very important to know you have a support system," said Gina Futrell, a 51-year-old with multiple sclerosis, who was among a large crowd gathered at Union Square for a chance to see the "Batkid" in action. "I have an extremely strong support system, and I hope he does too. He's such a little hero."
Batkid was called into service by police chief Greg Suhr and spent the day zooming from one "crime scene" to the next.
Accompanied by an adult Batman impersonator, Batkid rescued a damsel in distress from cable car tracks, captured the Riddler as he robbed a bank, and saved the San Francisco Giants mascot - Lou Seal - from the Penguin's clutches.
Miles was able to fulfil his wish through the Make-A-Wish Foundation, the city and volunteers who stepped forward to help. He was diagnosed three years ago, underwent chemotherapy treatment and is now in remission.
Batkid had a police escort worthy of a dignitary as he sped around the city in a black Lamborghini with a Batman decal, with officers blocking traffic and riding alongside him on motorbikes.
The White House sent out a tweet encouraging Batkid to "Go get 'em!" In a video recording, President Barack Obama said: "Way to go, Miles! Way to save Gotham!"
The crowds grew after each stop, reaching into the thousands by the time Miles got to Union Square for lunch at the Burger Bar atop Macy's. Spectators climbed trees and clambered up lampposts, and police and organisers struggled to keep a path open for the motorcade, which drove past onlookers lining the streets six-deep.
At Batkid's stop in the city's Russian Hill neighbourhood, a woman sat on the cable car tracks in a dress and thigh-high black boots. She had a handkerchief around her mouth, and her hands were bound behind her back.
Batman and Batkid sprang into action, with the aid of a trampoline, as the crowd roared. They rescued the woman and disabled a plastic replica bomb she was tied to.
The two masked superheroes then took off to nab the Riddler as he robbed a city bank. They later jetted to the Penguin's kidnapping of Lou Seal.
The five-year-old at first seemed overwhelmed by the outpouring, quietly working through each scenario with clenched fists and tight lips amid delirious chants of "Batkid, Batkid". But by the time he reached City Hall to receive a key to the city in front of the biggest crowd of the day, Miles was all smiles and bravado.
Though he did not address the crowd, he raised his fist twice and wore a grin as he was feted with chocolate, an FBI "raid jacket" and a San Francisco Police Department cap. A clothing company donated 10,000 dollars (£6,200) to Miles's family, and San Francisco mayor Ed Lee proclaimed November 15 to be "Batkid Day Forever".
Lawyer Melinda Haag unveiled an "indictment" charging the Penguin and Riddler with conspiracy as the crowd that stretched for streets roared with delight.
Miles's father, Nick Scott, was asked what the boy liked best about Batman. "The cape, I guess," he said.
The father thanked the crowd, organisers and the city for showing his son a good time.
"This is closure for us," Mr Scott said. "It has been a hard three years."
Miles, who lives in Tulelake in northern California, did not know what was in store for him and thought he was in San Francisco just to get a Batman costume so he could dress like his favourite superhero.
He was diagnosed with leukaemia when he was 18 months old and ended treatment in June.
Make-A-Wish has fulfilled similar wishes across the country. In Anaheim, a child became Batman's sidekick, Robin; and in Seattle a child was a secret agent, said Jen Wilson, a spokeswoman for the local organisation.
The San Francisco Chronicle, KGO-TV and thousands of volunteers participated in the event. At Union Square, the Chronicle distributed hundreds of copies of special edition newspapers with the headline "Batkid Saves City".
"This is off-the-hook San Francisco," Mr Suhr said.