After a long stretch of pretty weak-to-indifferent spinoffs as AMC has sought to milk life out of “The Walking Dead,” “The Walking Dead: Dead City” arguably delivers the most satisfying spinoff yet by combining the signature characters, played by Jeffrey Dean Morgan and Lauren Cohan. Throwing the pair into a zombie-ravaged Big Apple merely adds to the (OK, kind of depressing) fun.

Cohan’s Maggie, understandably, has never gotten over Negan (Morgan) beating her husband to death in front of her, which, setting aside the gimmicky cliffhanger, ranks among the grisliest sequences the original series ever produced (and that’s saying something).

Still, Morgan’s natural charisma made him one of the more beguiling characters in the flagship show’s later seasons, without sacrificing his sense of menace or, when necessary, ruthlessness. Maggie, similarly, hardened through the years, in a way that Negan can’t help but admire, while realizing that she’ll never get over her long-simmering animosity.

That serves as the backdrop for the premise, with Maggie coming to Negan to grudgingly ask for his help to get her abducted son back from a threat with which he might harbor particular insight, a sadistic heavy known as the Croat, played with thickly accented zeal by Željko Ivanek.

Jeffrey Dean Morgan in “The Walking Dead: Dead City.”

The mission requires traveling to Manhattan, where enough time has passed that deer roam the streets, and zombies, when alerted to potential meals, can literally rain down from skyscrapers. Adding to the intrigue, Negan is pursued by a dogged lawman (“Friday Night Lights’” Gaius Charles) tasked with bringing him in for past crimes, creating another layer of danger.

With veteran “Walking Dead” producer Eli Jorné serving as showrunner, “Dead City” would be stronger, frankly, if its six episodes constituted a true limited series, as opposed to leaving the door ajar for further installments. Then again, since the first show became a breakthrough hit, the entire franchise hasn’t exactly been characterized by knowing when to quit when it’s ahead, so that’s hardly a shock.

On the plus side, Morgan and Cohan (who also hold executive producer titles) frequently offered two of the best reasons to continue watching “The Walking Dead” down the home stretch, as other mainstays came and went, and the format here provides a more steadfast focus on both of them.

“Dead City” isn’t perfect, but after “The Walking Dead: World Beyond,” “Tales of the Walking Dead” and even the long-running “Fear the Walking Dead,” this first of several planned spinoffs following the series finale offers the best reason to reenter this post-apocalyptic world in years.

As they’ve been known to say around Manhattan, start spreading the news.