Tuesday's two "NCIS" series tell one story tonight in a crossover event.
It gets started on "NCIS" (7 p.m., CBS/Ch. 2), when Abby's homeland security think tank is compromised and she is found in possession of a real bomb. The team discovers the leader of the group has been murdered and a theoretical terror playbook has been stolen.
And then on "NCIS: New Orleans" (9 p.m., CBS/Ch. 2), McGee and Torres travel to Louisiana to partner with Pride and his team in the search for a missing homeland security theoretical terror playbook.
• Also tonight, eyewitness accounts of the 1992 FBI siege at Ruby Ridge include the daughter of Randy Weaver, the man arrested following a standoff with police, and the federal agents on the scene in an hourlong edition of "American Experience" (8 p.m., PBS/Ch. 7).
• And on "Independent Lens (11 p.m., PBS/Ch. 7), "Tower" uses animation to re-create the 1966 mass shooting at the University of Texas. It sounds crazy, but it's extremely well done and effective.
Elsewhere on TV ...
• 141st Westminster Kennel Club Dog Show (6 p.m., FS1): Day 2, from New York City.
• "The Middle" (7 p.m., ABC/Ch. 4): Axl, Sue and Brick tell a Frankie and Mike that their constant bickering is having a negative effect on them.
• "New Girl" (7 p.m., Fox/Ch. 13): On Valentine's Day, Jess tries to convince everyone she's happy being single.
• "Tough Mudder: The Challenge Within" (7 p.m., CW/Ch. 30): People struggling to overcome personal challenges put their teamwork skills, physical abilities and mental grit to the test on an excruciating obstacle course.
• "The Haves and Have Nots" (7 p.m., OWN): Jim gauges Veronica's loyalty to the group.
• "American Housewife" (7:30 p.m., ABC/Ch. 4): Greg's over-the-top romantic gestures conflit withKatie's yearning for a low-key Valentine's Day.
• "The Mick" (7:30 p.m., Fox/Ch. 13): Mickey's decides to stop being the cool aunt and lay down the law with the kids.
• "Bull" (8 p.m., CBS/Ch. 2): Benny defends a whistle-blowing army analyst who is being court-martialed.
• "Fresh Off the Boat" (8 p.m., ABC/Ch. 4): Jessica is excluded from the Neighborhood Watch because of her reputation as a non-team player; Eddie prepares for his first kiss.
• "This Is Us" (8 p.m., NBC/Ch. 5): Kevin stresses about the premiere of his play; Rebecca and Jack's Valentine's Day doesn't go as planned; Toby and Kate decide to get to know each other's biggest secrets.
• "Bones" (8 p.m., Fox/Ch. 13): Corpses that are linked to Booth's former Army unit turn up around D.C.
• "The Real O'Neals" (8:30 p.m., ABC/Ch. 4): Eileen discovers that Pat's new girlfriend is her nemesis.
• "Marvel's Agents of S.H.I.E.L.D." (9 p.m., ABC/Ch. 4): Coulson and the team engage in a deadly cat-and-mouse game as they work to rescue Director Mace.
• "Chicago Fire" (9 p.m., NBC/Ch. 5): Chief Anderson feels his authority is undercut by Chief Boden.
• "The Fosters" (9 p.m., Freeform): Callie makes an enemy in juvenile hall when she refuses a guard's propositions; Jude receives a second chance with Noah.
• "Being Mary Jane" (10 p.m., BET): Niecy's rash decision has some dire consequences.
• "Switched at Birth" (10 p.m., Freeform): Toby and Lily return from London and announce their plans to get married.
• "Face Off" (10 p.m., Syfy): The Ateams work to create beautiful snow queens inspired by a series of unique snowflakes.
• "Outsiders" (10 p.m. WGN): The animals aren't the only ones who bleed during the Farrell's winter hunt.
• "Escaping Polygamy" (11 p.m., A&E): Some who have escaped polygamy are tempted to go back.
• "Taboo" (11 p.m., FX): The East India Company declares war on James Delaney.
• "Teachers" (11 p.m., TV Land): Ms. Snap decides to run for School Council.
• "Detroiters" (11:30 p.m., Comedy Central) After a client inspires Tim and Sam to work less and live more, the guys buy a motorcycle instead of the production van they need.
• "Imposters" (11 p.m. Bravo) Maddie tries to hook her latest mark but finds herself drawn to a mystery man named Patrick.