SAN FRANCISCO (AP) -- Thousands of people in San Francisco on Friday were set to help a 5-year-old leukemia patient fulfill his wish to play Batman for a day -- and he didn't know it was coming.
With the help of the Make-A-Wish Foundation, Miles Scott, or Batkid, will rescue a woman, capture the evil Riddler as he robs a downtown bank and stop a kidnapping by another villain, the Penguin.
A grateful mayor Ed Lee will give Miles a key to the city after the "crooks" are caught.
KGO-TV says Miles thinks he's in San Francisco only to get a Batman costume so he can dress like his favorite superhero.
The boy will see a broadcast in the morning with city Police Chief Greg Suhr calling for his help. The San Francisco Chronicle, KGO-TV and thousands of volunteers are participating in the event.
The Chronicle will distribute special-edition newspapers with the headline, "Batkid Saves City," in Union Square, where people will gather, Someone has even provided a Lamborghini to serve as the Batmobile, the station said.
"This has turned into a full blown phenomenon," Suhr said Thursday.
Miles was diagnosed with leukemia when he was 18 months old, ended treatments in June and is in remission.
His father, Nick Scott, thanked the estimated 7,000 people who will help make his son's wish come true.
Make-A-Wish has fulfilled similar wishes across the U.S. One child became Batman's sidekick, Robin; and another was a secret agent, said Jen Wilson. a spokeswoman for the local organization.
AP writer Channing Joseph contributed to this story.