After a mysterious illness strikes children from military families, Gibbs and the team investigate the cause. Meanwhile, Abby and Jimmy partner with the Naval Medical Research Center to determine the strain of illness, all in hopes of delivering a cure before the holidays. Also, Director Vance struggles with forgiveness as his estranged father-in-law makes a surprise visit to his home.

It's the season finale of "The Voice" where host Carson Daly will reveal who America has chosen to be the winner. Adam Levine, Blake Shelton, CeeLo Green and Christina Aguilera star as the celebrity panel of coaches.

The 10 remaining contestants reach a milestone this week, as the competition goes from teams to singles. Wearing their new individual color shirts, the players meet host Alison Sweeney for a night-time "ring of fire" endurance challenge that involves holding a percentage of their individual weights. Alison also shares exciting news about an upcoming event that will be a "Biggest Loser" first for contestants, and sobering news that this week's weigh-in will end with a double elimination. Now that the teams have been disbanded, trainers Bob, Jillian and Dolvett are eager to switch it up and work out with new contestants this week. One player struggles with self-sabotaging negative thoughts, and two contestants make it to the coveted "One-derland" at weigh-in and say goodbye to weighing over 200 pounds. Then it's time for the dreaded red line, which will determine which two players will be going home.

After Les secretly found out that Seth was at Bill's Pawn Shop, Les confronted him, asking Seth why he would betray the family by visiting a competing pawn shop. Seth explained the real reason: he was branching out into consulting as a sideline - the very thing that another person that Seth hired tried to do for American Jewelry earlier. As being a consultant is tantamount to disclosing family secrets to strangers, Les gives Seth a choice: "Family, or nothing".

A senator's daughter is the victim of a home invasion. The team investigate to determine if it was a random crime or a targeted attack due to her father's crackdown on international cyber warfare. Meanwhile, Kensi's holiday spirit changes after she receives a surprise Christmas gift.

Josh and Bill are forced back to their day jobs after their shine runs blue. Chico, under financial stress, makes a hard decision that could risk it all. Tickle struggles to keep Tim's old territory supplied. Mark and Jeff move their liquor.

With Reese and Fusco absent, Sam and Finch take on a new Number: a man dying of a brain tumor. In the past, a young Finch pursues his interest in computers.

After Matty asks for permission to take Bailey to prom, Jenna reevaluates who she has become and who she wants to be.

Erik Prince

Jesse Tyler Ferguson, the Head and the Heart

Garry Trudeau, Cyndi Lauper, Alan Cumming

Paul Rudd, Cristin Milioti, a Top Ten List presented by Barbara Walters, Alt-J

Olivia Wilde, Julie Scardina, Johnny Mathis

Alyssa Milano, Wilford Brimley

The tense crime drama comes to an unmissable climax as Karl falls apart when the Truth Terrorist's change of direction becomes too much to bear.