'NCIS' Season 11 Episode 17 Spoilers: Keith Carradine Guest Stars, Backdoor Pilot for 'NCIS: New Orleans' Airs March 25

The next episode of "NCIS" will feature a special guest star.

Keith Carradine will guest star in the March 18 episode, "Rock and a Hard Place." The episode will focus on a bomb detonating at a military charity concert.

The synopsis for "Rock and a Hard Place" reads: "After a bomb detonates in the dressing room at a military charity concert, the NCIS team must determine if the target was a washed-up '80s rocker or if the bomb was part of a larger scheme. Meanwhile, Jimmy prepares for fatherhood."

According to The Talk Town, the next episode will be the last episode before Special Agent Leroy Gibbs (Mark Harmon) goes to New Orleans to investigate a crime, functioning as the backdoor pilot for "NCIS: New Orleans."

The episode "Crescent City" airs on March 25, and will feature the team working with the field office in the Big Easy to find out who killed a man who was connected to many of the NCIS agents.

On the last "NCIS," the series celebrated its 250th episode by bringing back Tony's father, who kept a secret from his son.

In "Dressed to Kill," Tony (Michael Weatherly) sees a man impersonating a Navy officer, and shoots and kills him in an alley, with his father (guest star Robert Wagner) as the sole witness. It turns out that the man who he shot had just come from shooting someone else.

The man was a private investigator, whose trail leads to the senator's secretary, who is very upset about the man's death.

It's discovered that the secretary was dating the P.I., and the investigator was dressed as a Navy officer because the man he shot was expecting to meet a Navy officer to analyze ports. The secret meeting had to do with a bill the senator was waiting to get passed.

Meanwhile, Tony's father says he has "great news" to share with his son, but keeps putting off telling him what the news is. Instead, he tells Tony that he's getting married again, but doesn't tell him anything about his fiancee.

Yet, during the murder investigation, Tony and Bishop (Emily Wickersham) see Tony's father going into a hotel room with a young pregnant woman.

After a lot of speculation, it turns out the pregnant woman is his fiancee's daughter. McGee Senior tells his son that his fiance is Linda, Tony's godmother and his mother's best friend. He insists that they did not have an affair while his mother was alive, but Tony still struggles with the news.

Tony tells Gibbs (Mark Harmon) that he feels like his father is betraying his mother, but Gibbs tells him that his father must feel the same way, and that's why he needs his approval about the impending marriage. Tony then gives his father his approval, and the two reconcile.

The next episode, "Rock and a Hard Place," airs Tuesday, March 18, at 8 p.m. EST on CBS.