Loyal viewers of the CBS show “NCIS” have seen several Hollywood celebrities guest star in previous episodes of the series. However, an upcoming episode will feature an appearance from the U.S. first lady Michelle Obama.

The U.S. first lady is set to appear in episode 22 of “NCIS” season 13, titled “Homefront.” Her special participation in the series is said to be linked to the “Joining Forces” initiative. In the episode, President Barack Obama’s wife will welcome Special Agent Gibbs (Mark Harmon) to the White House, E!News reported. Apart from Gibbs, the first lady will also meet the wife of a Marine, as well as other military spouses, for a special “Joining Forces” meet-and-greet.

“Joining Forces” is nationwide initiative that was launched in 2011 by Michelle Obama and Jill Biden, Vice President Joe Biden’s wife. The initiative was started to support service members, veterans, as well as their families through programs that tackle education, wellness and employment opportunities. In the upcoming “NCIS” episode, spouses of actual military servicemen were also used as extras for the White House scene.

“NCIS” producer Gary Glasberg said in a statement posted on the CBS website: "It was such a pleasure working with First Lady Michelle Obama and it's our honor to support the 'Joining Forces' initiative and the military families that benefit from it." He added that being able to film an episode inside the White House was “a dream come true” for the show’s cast and crew members.

However, Glasberg also revealed in an interview with USA Today that they were not supposed to film the scene at the White House. He said the “Joining Forces” meet-and-greet scene was originally planned to be shot at the show’s set in California. The filming plans were changed due to scheduling conflicts and the first lady then invited the “NCIS” cast and crew to film the scene at the White House instead.

"I brought a crew and we spent a day in the White House … We feel honored and privileged,” Glasberg added.

The U.S. first lady’s appearance in “NCIS” comes a few episodes ahead of cast member Michael Weatherly’s impending exit from the series. The actor, who portrays the character Special Agent DiNozzo, is set to make his last appearance in the upcoming season 13 finale.

“Homefront” will air on May 3, while the final episode of season 13 will be released on May 17.