Worth Watching: 'Cobra Kai' Returns, A Mother of a 'Brockmire,' Luke Perry's Final Act on 'Riverdale'

A selective critical checklist of notable Wednesday TV:

Cobra Kai (streaming on You Tube Premium): The breakout Karate Kid sequel is back for a second season, starring Ralph Macchio and William Zabka as adult, but still sparring, versions of Daniel LaRusso and bully Johnny Lawrence, who now run rival dojos. Daniel's, naturally, is an homage to the late Mr. Miyagi, and it's the training home for Johnny's estranged son, Robby (Tanner Buchanan) as well as Daniel's own daughter, Samantha (Mary Mouser). The spoiler in the rivalry: the return of sinister war vet John Kreese (Martin Kove), who'd like to take back Cobra Kai.

Why 'Karate Kid' Fans Will Especially Enjoy 'Cobra Kai' Season 2See Also

Why 'Karate Kid' Fans Will Especially Enjoy 'Cobra Kai' Season 2

Ralph Macchio teases the 'feel-good comfort food' of the sophomore run, and how it sets up Season 3.

Brockmire (10/9c, IFC): "You'll be a lot better when this morality phase is over." Is that any way for a mother to talk? The answer is yes, when Mother Brockmire is played by the remarkable Linda Lavin, who pays a darkly hilarious visit to son Jim (Hank Azaria) and daughter Jean (Becky Ann Baker), whom she abandoned as children. An expert at "emotional violence," Lorraine is the sort of bad influence who could drive Jim back to the bottle. So say a special prayer for our favorite disgraced sportscaster during his turbulent road to recovery.

What We Do in the Shadows (10/9c, FX): In an especially funny episode of my other favorite cult comedy, about misfit vampires living the life of the undead in Staten Island, Laszlo (Matt Berry) is fit to be tied — or, rather, caged — when he's captured by Animal Control while in bat form. It's up to Nandor (Kayvan Novak), servant Guillermo (Harvey Guillén) and deadly dull Colin (Mark Proksch) to come haplessly to his rescue. Where's Nadja (Natasia Demetriou)? Busy making time with the latest reincarnation of her eternal lover Gregor — who now goes by Jeff and works as a mundane security guard. Which would be disappointing if he weren't played with such deft, dim charm by Murphy Brown's Jake McDorman.

New Details on Luke Perry's Final 'Riverdale' Episode as Fred AndrewsSee Also

New Details on Luke Perry's Final 'Riverdale' Episode as Fred Andrews

The actor passed away in March and has already appeared in three episodes posthumously.

Inside Wednesday TV: A poignant moment for The CW's Riverdale (8/7c), as the drama airs the late Luke Perry's final scenes as Fred Andrews, once again offering wise parental advice to Archie (KJ Apa). "A beautiful, true moment between a father and his son. Wish these scenes could go on forever," tweeted executive producer Roberto Aguirre-Sacasa. A sentiment shared by all… Echoing one of Grey's Anatomy's more harrowing episodes from years ago, NBC's Chicago Med (8/7c) goes into lockdown when an active shooter busts in and holds the medical staff hostage… Things aren't much calmer on NBC's Chicago Fire (9/8c), when the crew is stuck in their firehouse without power during a terrible storm… Dr. Wolfgang Dittus has spent A Life Among Monkeys (9/8c, Smithsonian Channel), observing the toque macaques for over 50 years in the world's longest continuous monkey study. In this special, set in the picturesque ancient ruins of Polonnaruwa in Sri Lanka (in the news these days for much sadder reasons), Dr. Dittus reveals what he's learned over the decades about the monkeys' social order… HGTV's Boise Boys (11/10c), aka Clint Robertson and Luke Caldwell, are back for a second season of ambitious renovation projects in Idaho's capital city.