NCIS stars Pauley Perrette and Sean Murray made it clear that fans must tune in to Tuesday’s Christmas episode.

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Perrette, who plays Abby Sciuto, and Murray, aka Timothy McGee, took to Twitter on Saturday to send their messages.

According to CBS, the episode, titled “House Rules,” will show the NCIS team consulting with “three cyber-terrorists they imprisoned after a city-wide Internet shutdown the week before Christmas.”

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During the episode, McGee will also think about the case as well as “Gibbs' infamous rules as he pens a heartfelt letter to his father.”

The Christmas episode airs on Tuesday, Dec. 16 at 8 p.m. EST on CBS.

See the teaser below:

Tags: NCIS