Transcript for 'Batkid Begins' Film on 5-Year-Old Leukemia Survivor in the Works
story behind the story that warmed everyone's heart. The bat kid, the 5-year-old diagnosed with leukemia whose greatest wish was to be a real-life super hero and save his hometown of San Francisco. Now, a new documentary takes us behind the scenes of his emotional journey, to villains and cancer. A damsel in distress, a bank about to be robbed. And a beloved mascot, kidnapped. With two killers on the loose San Francisco needs a hero. We need you, cape crew aider. And, bring the bat kid. He captured the heart of the nation last fall when he transformed into bat kid to save his city. Now, a new documentary reveals how it all went down. There have been plenty of super hero wishes that they have made, nothing was like this. Behind scenes, they're making costumes and the 5-year-old had already fought leukemia. It was time to take on the individual villains. He was diagnosed in April, that is when the whole town came together. When his wish went viral it took on a life of its own. The city is expecting thousands of people to participate. The scale of this production is unbelievable. It is remarkable, leaving his parents overwhelmed and grateful. I'm like okay, well, there are a lot of cops around. He needs a car seat. 25,000 people lined the streets to cheer for miles, hoping to pull off one of the most elaborate escapades in history. All of these people are not at work today, they came to watch our son parade around town. As he went around town, the exploits went viral. With miles in remission, they are raising money to support the fund, over $50,000 to help other San Francisco charities, big shoes to fill for the next charity.
This transcript has been automatically generated and may not be 100% accurate.