"NCIS" will celebrate a remarkable 300 episodes on Tuesday night and spotlight an inspiring organization that is helping military veterans returning from Iraq and Afghanistan to make a successful transition back to civilian life. Special guest star Taye Diggs will play one of those veterans that is struggling with Post Traumatic Stress Syndrome (PTSS), but could find some peace through music and the MusiCorps Wounded Warrior Band.

The MusiCorps Band is a conservatory-level music rehabilitation program in response to the crisis of service members returning from Iraq and Afghanistan. The program was established at the Walter Reed Army Medical Center in 2007 by founder Arthur Bloom, a composer. Bloom got the idea visiting a soldier at the facility who had lost his leg in a roadside bomb and wanted to know if he could ever play the drums again.

"Like anybody, I wanted to help him. But stepping back, I looked at the circumstances of all of these injured veterans, who may be at Walter Reed for what could be years with little to do outside of medical appointments. And I thought: 'What if we made a program for anyone, regardless of whether they played music before, who wanted to do classical or metal or rock?'" Bloom said. "We put it together as an experiment and, one after the next, everyone who could do it wanted to do it, and it just took off."

The band has played with legendary musicians Roger Waters (Pink Floyd), cellist Yo-Yo Ma and Sheryl Crow and at famous venues such as the Kennedy Center for the Performing Arts, the Grand Ole Opry and Madison Square Garden. The wounded warrior musicians have also performed on PBS and "The Colbert Report."

Any injured veteran who wishes to learn or relearn an instrument can participate whether they played or performed prior to their injury. Hundreds of veterans have learned how to play instruments, write songs and arrange music.

"We rehearse, we learn, we play," Bloom said. "All of the professional musicians who come here to teach are blown away at how good the wounded warriors get at music."

"NCIS" showrunner Gary Glasberg learned about the MusiCorps Band from executive story editor Gina Monreal, who wrote episode 300. They had discussed incorporating the organization into an episode and the 300th was a perfect fit.

"It's really amazing what they do, so we've been talking about doing a storyline that was sort of focused on them and a character working with them," Glasberg said. "And as we got closer to 300, knowing the elements that we write to include in a special episode like this, where we want something for everyone - the action and suspense and the humor that we usually try to deliver - and to have a patriotic emotional core to it as well, this seemed right."

MusiCorps accepts monetary donations as well as instruments and equipment. Skilled musicians can also volunteer their services as teaching artists.

Diggs performed a soulful cover of Leonard Cohen's "Hallelujah" with members of the MusiCorps Wounded Warrior Band during the 300th episode of "NCIS," which aired on Tuesday, March 15.