'NCIS' Season 13 episode 18 spoilers: Team marks 300th episode titled ‘Scope’ with guest star Taye Diggs

After a brief hiatus, “NCIS” returns with a brand new episode, reaching the 300th mark. The show promises a dramatic run on Tuesday, as it centres on the lives of “real-life heroes,” the wounded military men. Titled “Scope,” the upcoming installment features a case led by Leroy Jethro Gibbs (Mark Harmon), as he tries to connect with a wounded veteran for crucial information.

“Private Practice” star Taye Diggs has signed up to appear on the Mar. 15 run to play the role of Marine Gunnery Sergeant Aaron Davis. He joins other “NCIS” cast members Agent Anthony DiNozzo’s (Michael Weatherly), Timothy McGee (Sean Murray), Eleanor Bishop (Emily Wickersham) and Jimmy Palmer (Brian Dietzen). Jon Cryer appears on the upcoming episode as Dr Cyril Taft, Leon Vance (Rocky Carroll), Abby Sciuto (Pauley Perrette) and Dr Donald Mallard (David McCallum).

Spoiler alert! This update contains more "NCIS Season 13" spoilers. Read on at your own risk if you have not watched the latest episode.

TV Guide reports that on Tuesday’s episode, the crew revisits an ambush case involving a group of Special Ops snipers in Iraq. Although the case happened six months ago, the investigation has been re-opened after an American couple gets attacked in the same location. Gibbs recognises that the account of the only survivor would be substantial to the case. Gibbs attempts to get ahold of the wounded warrior, who is being treated for PTSS at Walter Reed Medical Center.

“NCIS” also posted sneak peeks of its Mar.15 episode on its YouTube page. On the first preview, the team looks at the profile of Marine Gunnery Sergeant Aaron Davis, the lone survivor of the ambush. A scene shows Gibbs trying to assure Davis that there’s nothing that he could have done, but Davis brushed him off. On another part of the video, Dr Mallard says that a single act can have ramifications beyond one’s own comprehension. Throughout the clip, Davis is also seen singing with the MusiCorps band, which served as the inspiration behind the episode.

“It’s really amazing what they do,” NCIS executive producer Gary Glasberg told TVLine, referring to MusiCorps. He wrote the 300th episode with executive story editor Gina Monreal. “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,” Glasberg said.

Despite a special attention given to Harmon’s character and his interaction with Diggs, Glasberg said will have their share of the limelight. “Everybody gets a piece of the pie, and there are some fun, unexpected, juicy tidbits that will be in there,” he said.

The Mar.15 episode of “NCIS” is directed by Tony Wharmby. KSiteTV reports that “Scope” include guest stars Laura San Giacomo (Grace Confalone), Samantha Logan (Riley Davis), Maureen Sebastian (Navy Chief Petty Officer Elaine Dodd), Paul Bartholomew (Spencer Dodd), and Christopher Goodman (NCIS Special Agent Michael West).

Find out what happens next on “NCIS” Season 13, which airs in the US on CBS every Tuesdays, 8/7c.