Courtesy Make-a-Wish Foundation

Alex Lelenoa, a 7-year-old boy who was diagnosed with leukemia three years ago, thought he was staying home from school Monday for yet another doctor's appointment.

Instead, Alex, of Anaheim, Calif., was greeted at his front door by a local police officer who told him he had an unlikely but important task for the day: to save the city of Anaheim from the bad guys.

"He was immediately game," Sarah Pizzaruso, spokeswoman for the Make-a-Wish Foundation's Anaheim chapter, told Goodmorningamerica.com. "He didn't pause for a second. He put on his shoes and said, 'Let's go.'"

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The Make-a-Wish-Foundation reached out to the Anaheim Police Department for help after Alex told the foundation's "wish granters" that his dream was to be a superhero, specifically Robin, the sidekick to Batman.

Alex's day started at the police station, where he was named an honorary police officer, met his Batman - a stuntman in character - got his Robin costume and got a briefing from the city's police chief on what he and Batman needed to accomplish.

From there, Alex and Batman went to a local amusement park where Alex used his signature move - clapping his hands three times, arching his arms and putting his wrists together - to "freeze" the cowboys so he and Batman could rope them up.

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Then it was on to the local airport where Alex and Batman boarded a helicopter so they could spot the Riddler's symbol on the ground, a question mark. They landed at the stadium of the Anaheim Angels - where Alex got a jersey, a bat and a "thank you" for saving the city from the team's general manager - before driving off in a real-life Batmobile to the on-the-ground location of the Riddler's question mark they saw earlier from the sky.

Nearly six hours later, Alex's dream day ended in a battle with the Riddler - complete with fireworks and pyrotechnics - that saw the Riddler being thrown in a SWAT team vehicle by the heroes, Alex and Batman.

"He took it like a true superhero," said Pizzaruso. "He was very proud he had captured the bad guys. He posed with his superhero, made sure to keep his mask on and played along with every single part of it."

Alex, according to Pizzaruso, even kept his Robin persona up at the grand finale party back at police headquarters that included more than 200 friends, family, police cadets and a local high school's cheerleading squad.

"He waved to the crowd from the stage," Pizzaruso said.