What fans can expect in eason 14 of "NCIS" remains a big mystery given all the character changes the show has undergone over the last several months.

One thing viewers won't have to endure is watching series newcomer Wilmer Valderrama trying to morph into the popular Tony DiNozzo character played by the now departed Michael Weatherly.

"[Weatherly] had a fantastic journey with the show," said the former "That 70s Show" star now cast in the most popular drama series on TV as Special Agent Nicholas "Nick" Torres. "The truth is there's no shoes to fill, I'm definitely wearing my own."

Valderrama Cast as 'Loose Cannon'

Valderrama's character is billed as a "once-grounded NCIS field agent who accepted a deep cover assignment years ago and never resurfaced."

Given his disappearance, many agents weren't sure if was still on the job or even alive before he mysteriously turns up as "an unpredictable, charismatic loose cannon."

The 36-year-old actor is set to join fellow newcomers Jennifer Esposito (Special Agent Alexandra "Alex" Quinn) and Duane Henry (MI6 Officer Clayton Reeves).

"I'm excited because as a new member of NCIS I get to bring a new energy to it, a different dynamic," said Valderrama.

Meanwhile, longtime series regulars Pauley Perrette (Abby Scuitto), Rocky Carroll (Leon Vance), Sean Murray (Tim McGee) and David McCallum (Donald "Ducky" Mallard) all recently signed on for two more seasons on the show.

Fellow original cast member Mark Harmon (Agent Leroy Jethro Gibbs) also resigned for two more seasons back in February.

Viewers Still Tuning in

"NCIS" averaged 20.54 million viewers for first-run episodes during its just concluded 13th season. The popularity of the show has spawned such network spin-offs as "NCIS LA" and "NCIS New Orleans."

Season 14 debuts on September 20 on CBS (8 p.m. ET).

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