'NCIS' season 14 episode 18 spoilers, news: Team's undercover mission gets compromised; former cast member Michael Weatherly speaks on leaving show

An NCIS mission is compromised while Reeves (Duane Henry) is undercover on the upcoming episode of CBS' long-running procedural drama "NCIS" season 14.

Titled "Willoughby," the show's midseason premiere will see Qasim Nasir's (Rafi Silver) return as he works on a case with his girlfriend Bishop (Emily Wickersham). According to the official synopsis, the NCIS team looks for new leads after an undercover operation is compromised. The agents must deal with a businessman who uses acts of terror to manipulate the stock market. When Qasim returns, he and Bishop team up and find a break in the case together.

Willoughby is the name of the team's operation which was first mentioned in this season's 9th episode titled "Pay to Play." The said episode saw Quinn (Jennifer Esposito) discovering the Operation Willoughby file sitting on Reeve's desk. The mission had been delayed for six months because no one was willing to work on it. However, Reeves explained that he had his reasons for accepting the task.

The current season of "NCIS" introduced new characters, including Esposito and Wilmer Valderrama. However, if there is one familiar face fans miss the most in the show, it's Michael Weatherly. The former cast member known for playing Tony DiNozzo decided to exit the series last year and is now the lead star of the rookie CBS drama "Bull." Speaking with TV Line, Weatherly admits he still misses the show he called home for 13 years.

"You know, I miss that specific camaraderie," the actor said, adding, "I miss the people and smiles, the laughter. But I have had some good laughs on 'Bull'! I felt very satiated by my experience at 'NCIS.' As I said to you last time, it was a full circle and I felt ready to move on, and that has definitely been the case. I have no remorse or misgivings about what went down."

The 14th season of "NCIS" returns tonight at 9 p.m. ET on CBS.