Inside this make-shift Kirkland studio, Grammy-winning composer Mateo Messina is putting the finishing touches on his latest symphony.

“I'm calling it Epoch, not epic but epoch e-p-o-c-h. It's basically about what is significant in a lifetime,” Messina said.

A fitting theme for this unconventional maestro. Since his was 23, Mateo has written and produced an annual concert benefiting Seattle Children's Hospital. So far, it’s raised more than a million dollars through his foundation, LUMA Guild.

It's a legacy that's eclipsed his success as a Hollywood composer working on dozens of films and TV shows.

“I really am so grateful but it doesn't even compare to how much working with kids and volunteering at the hospital has filled my heart,” Messina said.

Each year features a unique musical experience with unforgettable performances like the time Mateo teamed up with Alice ‘N Chains to cover Led Zeppelin's ‘Kashmir.’

“It's this epic iconic rock song and I'm floating about that far off the podium,” he said, “I don't even think I'm standing on it and I'm just like this is a moment.”

He’s also staged a battle between the University of Washington drum line and a 50 person Brazilian drum line.

But the occasions that stand out the most strike a more emotional chord.

“Everybody leaves that night feeling warm and fuzzy just like 'I'm so glad I went. I had a great time,’ he said. “And they're a part of something that's very different because this concert is unlike any other concert. There's nothing common about it.”

The 20th annual Seattle Children's benefit concert takes place Friday, November 10th at Benaroya Hall in Seattle. Tickets are still available.