What’s On: Diana Speaks, ‘Preacher’ Freaks, the Mooch Visits Colbert

Diana: In Her Own Words (9/8c, National Geographic Channel) As in life, TV can’t get enough of Princess Diana 20 years after her untimely death. Retrospectives abound this summer, but the latest special avoids the usual talking-head royal experts to go straight to the source, featuring never-before-broadcast recordings of a 1991 interview Diana gave to a friend on behalf of journalist Andrew Morton. Her words are illustrated by archival footage and photographs, resulting in an unusually personal portrait of the cultural icon.

Preacher (9/8c, AMC): The war is on as Herr Starr’s (Pip Torrens) army in white converges on Jesse (Dominic Cooper) and his dysfunctional team, leading to a tense vigil and one of the more creative uses of an Edith Piaf classic that I didn’t regret at all. And wait until you meet Brad, who’s bad news for another musical icon. Torrens’ deadpan depiction of demonic menace is a case study in inventively droll villainy, something The Walking Dead might want to study before launching another tiresome antagonist like Negan upon us.

Late Show With Stephen Colbert (11:35/10:35c, CBS): The Mooch is back! Not the parody version portrayed by Mario Cantone on Comedy Central’s The President Show, or in prime time by Bill Hader on last week’s Saturday Night Live: Weekend Update special. This is the real deal, as quickly ousted White House lightning rod Anthony Scaramucci goes face to face with one of TV’s most popular political satirists, and good luck matching wits. That takes an unusual amount of nerve. Or ego. Or both.

Inside Monday TV: Reality checklist: Having already stirred controversy from down Mexico way, the fourth season of ABC’s Bachelor in Paradise (8/7c) gives retreads from the Bachelor franchise another chance at exposure, if not love. … By comparison, NBC’s American Ninja Warrior (8/7c) looks like good clean fun, with 30 competitors hoping to move on from the city finals in Cleveland to the upcoming finals in Las Vegas. … TNT’s Dallas remake was a bust, but Bravo’s The Real Housewives of Dallas (10/9c) carries on, for a second season of manufactured drama that might make Sue Ellen reach for the bottle again. … Or you could opt for a more sobering reality, as the summer CBS newsmagazine CBSN: On Assignment (10/9c) files a timely report from Guam. Correspondent Vladimir Duthiers gained exclusive access to the territory’s Andersen Air Force Base, interviewing B-1 pilots and reporting on the military’s plans there, and in South Korea and Hawaii bases, to defend if necessary against North Korea.