Ed Perkins’ documentary “The Princess” (HBO, 8 p.m.) sets itself apart from other films about the beloved Diana, covering the time from her engagement to her death in 1997, but using only archival footage, given new context given time and new scoring. 

Primus and Ween are the headlining bands for “South Park: The 25th Anniversary Concert” (CNN, 8 p.m.) in which creators Matt Stone and Trey Parker celebrate their groundbreaking cartoon series. 

“Say Yes to the Dress” (TLC, 8 p.m.) looks back at 20 seasons. 

Katrine is threatened with a truth drug on the second episode of “Red Election” (Ovation, 7 p.m.).

In the made-for-TV “Romance in Style” (Hallmark, 8 p.m.) Jaicy Elliot plays a designer who encourages a publisher (Benjamin Hollingsworth) to include plus-size fashion in its pages. 

Less romantic is the thriller “In Love with My Partner’s Wife” (Lifetime, 8 p.m.) in which a police detective finds his partner is abusing his wife and steps in. Gina Vitori, Andrew Space and Jonathan Stoddard star. 

“First Blood” (A&E, 9 p.m.), the series that spotlights serial killers, ends its season by featuring Henry Louis Wallace, aka Bad Henry, who killed a number of young Black women in Charlotte, N.C. 

Also having their finales: “Steal This House” (HGTV, 9 p.m.) and “Panic 9-1-1” (A&E, 10 p.m.).