“CROSSBONES”: Lowe (Richard Coyle), right, learns the ulterior motive of Blackbeard (John Malkovich) for keeping him around. (Francisco Roman/NBC)

“Dateline NBC” (NBC at 8 p.m.) investigates the nearly two-decade-long mystery behind the death of Gary Triano, a successful entrepreneur in Arizona who was killed by a car bomb in 1996.

The Harry Potter franchise gets the red-carpet treatment on “Live From the Red Carpet: Diagon Alley” (E! at 8), a 30-minute special commemorating the opening of the famed and extensive cobbled wizarding shopping area at Universal Studios Florida.

The legends lurking behind a giant statue of Saint Urho, a fanciful fortress in the middle of nowhere and the bats residing in New Mexico’s Carlsbad Caverns that were used for military purposes are explored on “Monumental Mysteries” (Travel at 9).

RETURNING SHOW: “Cold Justice” (TNT at 9) returns for the final episodes of Season 2 with an investigation into the death of a woman who was stranded in a parking lot.

“Frederick Law Olmsted: Designing America” (WETA at 9:30) profiles the life and extensive career of landscape architect Olmsted, one of the primary designers of Central Park in New York and the U.S. Capitol grounds.

“Real Time With Bill Maher” (HBO at 10) hosts a roundtable with journalists Ta-Nehisi Coates, Glenn Greenwald and Kristen Soltis Anderson, veterans advocate Paul Rieckhoff and musician Mike Shinoda.

Blackbeard and Lowe work together to save Kate on“Crossbones” (NBC at 10) before Lowe learns of the diabolical pirate’s ulterior motive.

SERIES PREMIERE: Host Marlon Wayans and his comedy pals and family members put 10 comedians through a barrage of tests and challenges to find out which of them is the funniest on the new competition series “Funniest Wins” (TBS at 10) .

The “Independent Lens” (WETA at 10:30) docu-series brings us “The New Black,” a short film profiling the African American community’s debate over marriage equality and LGBT rights.

Actress Amanda Seyfried and comedian Will Ferrell are on “The Tonight Show Starring Jimmy Fallon” (NBC at 11:35), along with musical guest Chad Smith.

Comedian Dave Chappelle stops by the “Late Show With David Letterman” (CBS at 11:35) in this repeat episode from earlier in the month. Other guests include Laura Prepon from “Orange is the New Black” and the Orwells.

Spelling bee champions Sriram Hathwar and Ansun Sujoe come to “Jimmy Kimmel Live” (ABC at 11:35), with rapper Curtis “50 Cent” Jackson, actress Jenny Slate and musical guest OneRepublic.

Rachel Lubitz