NCIS: After a mysterious illness strikes children from military families, Gibbs and the team investigate the cause. (Sonja Flemming/CBS)

Gibbs and the team investigate a mysterious illness striking dozens of children from military families on “NCIS” (CBS at 8 p.m.), while Abby and Jimmy partner with the Naval Medical Research Center to determine the exact strain of the outbreak.

Actor Richard Harris narrates the special, “Red Metal: The Copper Country Strike of 1913” (PBS at 8), which is a look back at a strike in Michigan that was punctuated by tragedy when 73 people, mostly children, died in what came to be known as the Italian Hall Disaster after “fire” was yelled at a union Christmas party, causing a stampede for the exit. The event was memorialized by the Woody Guthrie song “1913 Massacre,” which is performed by Steve Earle in this hour-long special.

The teams are dissolved and the 10 remaining players compete against each other on “The Biggest Loser” (NBC at 8), beginning with an endurance challenge and a double elimination.

FINALE WATCH: The season five champion of “The Voice” (NBC at 9) is announced on the live final-results show.

On “How Sherlock Changed The World” (PBS at 9), forensic scientists, crime historians and Sherlockian experts reveal for the first time the astonishing impact Arthur Conan Doyle’s creation had on the development of real-life criminal investigation and forensic techniques.

RETURNING SHOW: “Hardcore Pawn” (truTV at 9) returns for its eighth season with Les suspicious about Seth’s loyalty and the possibility that he’s doing business with a competitor.

A wanted gang member is tracked down on “Marshal Law: Texas” (TNT at 10), a teen goes missing after allegedly stabbing his mentor 50 times and Max Pinon visits an exceptionally violent woman.

The mystery behind the creation of the Machine on “Person of Interest” (CBS at 10) is solved when viewers are shown a series of flashbacks from Finch’s teen years that provide some insight.

Actors Paul Rudd and Cristin Milioti come to the “Late Show With David Letterman” (CBS at 11:35), along with a Barbara Walters Top 10 list and a musical performance from Alt-J.

Actress Olivia Wilde and animal expert Julie Scardina are on “The Tonight Show With Jay Leno” (NBC at 11:35), with musical guest Johnny Mathis.

Actors Mark Wahlberg and Bruce Dern join “Jimmy Kimmel Live” (ABC at 11:35), with musical guest Poliça.

— Rachel Lubitz