NCIS: Los Angeles will continue to dig into Sam Hanna's past as season 6 continues.

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Viewers will be introduced to the agent's teenage son in the series' Christmas episode, "Humbug," but the topic of military fathers and their military school sons will first be broached in "Reign Fall."

Set to air on Dec. 8 (just one week before Isaac Hanna comes home from military school for the holidays), "Reign Fall" will see Callen's (Chris O'Donnell) team investigate when someone starts murdering marines. The only link between the victims will be their sons' education.

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Although no one else from the Hanna family will appear in the episode, the case will hit close to home for Sam (LL Cool J) on more than one count. "Reign Fall" will see the former Navy SEAL reflect on his own relationship with his father, a character that has not come up over the last six years.

Scroll through the photos above to see what's in store for the season's tenth episode.

Find out more when NCIS: LA airs Mondays at 10 p.m. ET on CBS. Click the video below to see a preview for the series' next episode, "Traitor."