Major Crimes (9 p.m., TNT) – When three 15-year-old boys vanish from a Catholic school field trip in the premiere of the sixth and final season, Major Crimes is ordered to treat the disappearance as a critical missing. This final season is a fairly short one, with the finale coming on Jan. 16.
Also on tonight . . .
Finding Your Roots (8 p.m., UNC-TV) – Actors Scarlett Johansson, Paul Rudd and John Turturro learn about their immigrant ancestors.
Lethal Weapon (8 p.m., Fox) – Murtaugh and Riggs investigate the death of a person about to win a horse racing bet.
This Is Us (9 p.m., NBC) – Trick-or-treating with the 10-year-olds goes awry for Jack and Rebecca.
blackish (9 p.m., ABC) – An incident at school threatens Junior’s future at his beloved Valley Glen Prep.
At Home with Amy Sedaris (10:30 p.m., truTV) – Amy Sedaris instructs on the perfect handmade gifts. Stephen Colbert guest stars.