Michael Weatherly
NCIS actor Michael Weatherly has been arrested for DUI. Here, he arrives at the 2014 People's Choice Awards in Los Angeles, California January 8, 2014. Reuters

"NCIS" Season 12, Episode 5, titled "The San Dominick," airs Tuesday, Oct. 21, on CBS. In the previous episode, Gibbs (Mark Harmon) -- and his famous gut -- give FBI Agent Leia Pendergast (Stephanie Jacobsen) a clear sign of approval. In this week's new episode, one of the show's favourite guest stars returns.

Spoiler alert: This feature contains NCIS Season 12 spoilers. Read at your own risk if you have not watched the previous episodes and have not seen the NCIS 12x5 promo video.

Tony DiNozzo (Michael Weatherly) meets his "Princess Leia" in NCIS Season 12, Episode 4. That Gibbs got Pendergast involved in a creative strategy against a shady Russian diplomat shows promise of the new character's return.

Many viewers are also speculating they have not seen the last of FBI Agent Leia Pendergast in NCIS Season 12. TV reports are saying she could be the first relationship Tony would have since the exit of Ziva David (Cote de Pablo).

In this week's new NCIS episode, however, an already recurring guest takes the spotlight. CGIS Special Agent Abigail Borin (Diane Neal) returns to solve a case that involves pirates. (Scroll down to watch the CBS NCIS 12x5 promo video.)

"Gibbs spots a dead man in the water during a joint Coast Guard and NCIS training exercise at sea. The investigation reveals the man is a missing crew member from a ship 60 nautical miles away. Upon boarding the ship for questioning, Gibbs discovers the vessel has been commandeered by pirates," reads the NCIS Season 12, Episode 5 synopsis on TV.com.

In other NCIS Season 12 updates, Abby (Pauley Perrette) is dating someone new, and McGee (Sean Murray) - who is still in a relationship with Delilah (Margo Harshman) - is pulling a "protective big brother" act. Ducky (David McCallum) reunites with his old love in London, and Jimmy Palmer (Brian Dietzen) is getting himself more involved in the NCIS operations outside the lab.

WATCH: NCIS Season 12, Episode 5 Promo Video | CBS on YouTube ('The San Dominick')

NCIS airs Tuesdays on CBS.

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