I can’t think of a simple way to outline the Amazon TV series “Catastrophe” without having it sound like a recipe torn from the fat, musty, dog-eared encyclopedia of sitcom clichés. Tall, goofy American guy and feisty Irish woman have a brief fling in London; she accidentally gets pregnant; he stays and they try to build a relationship. I could say it’s “Knocked Up,” paired with the presence of what TV expert Jump T. Shark once named as the greatest sitcom killer ever known to man: a baby. Actually, two babies.
But staleness does not ensue on the show, which returns with a second six-episode season on Friday. “Catastrophe” is a thoroughly enjoyable comedy that brings vigor and charm to a familiar TV trope. In that way, it’s something like HBO’s “Togetherness,” Hulu’s “Casual,” and Netflix’s “Love”; the writing transforms generic comic ideas such as odd couples, fish out of water, and singles looking for love into naturalistic, unhurried pleasures driven by very specific characterizations. The acting on all of these shows, too, is unforced and mugging-free. Like romantic indie films by the likes of Noah Baumbach, they emphasize tone and the follies of human nature over punch lines. They’re proudly catchphrase-free.
Written by its stars, Rob Delaney and Sharon Horgan, who play Rob and Sharon, “Catastrophe” is about the challenging process of love and family after marriage. It’s almost as simple as that, if you strip it down to pure concept. The second season picks up a few years after season one, with Sharon now nine months’ pregnant with her and Rob’s second child. He’s coping well and working at a pharmaceutical company, but the barbed Sharon, on leave from her teaching job, is on the verge of an angry depression. She’s uncharmed by the mommy life, and particularly turned off by the “mombies” — child-centric mothers who are like zombies — at a play group. Her effort to be amused and ironic about mothering with the ladies goes over like a lead balloon.
Humor is one of the things that Rob and Sharon share, and it’s a large part of why the two actors and characters have fantastic chemistry. Their passionate, silly, oddball connection floats the show. They’re both able to climb out of difficult and explosive conversations — about sex, about money, about parenting — with the help of warped jokes. They can banter about, say, their child Frankie’s penis size in a way that is hysterical, even if the mombies would sneer. They form one of TV’s most believable couples, as they hit all the notes — convincing arguments, cute but not smarmy makeup sessions, unromanticized sexual encounters.
Delaney, originally from the Boston area, is a Twitter hero, with a feed built on twisted quips and irreverence. But his character on “Catastrophe” is softer — a good-natured giant who, like Delaney, has been clean and sober for years. At one point in episode 2, after a potential friend rejects Sharon for being too needy, Rob proudly and loudly tells the woman off while standing in a movie queue. “Do you know how smart she is?” he says in the middle of his tirade. “She’s gonna have to explain this movie to me after we see it. I won’t get it.” It’s as lovely, funny, and sweetly self-negating a defense as a spouse could wish for.
Horgan brings a winningly wry affect to Sharon’s tightly strung temperament. At moments, with her timing, she reminds of Emma Thompson — which is a very good thing. No matter how irritated Sharon becomes, not just with the mombies but also with her father, who is showing signs of dementia, she is always ready to break for a laugh. The supporting characters are uniformly entertaining, with Ashley Jensen (from “Extras”) a standout as Sharon’s frenemy and Carrie Fisher as the worst cross-continental mother-in-law ever — “a malevolent hemorrhoid of a woman,” as Sharon calls her to her face in the premiere. But ultimately it’s Sharon and Rob who make the show worthwhile.
“Catastrophe” passes by much too quickly, as each episode feeds seamlessly into the next. It leaves me wanting more, craving another six-pack, which is always a pleasant feeling.
CATASTROPHE
Starring Rob Delaney, Sharon Horgan, Carrie Fisher, Mark Bonnar, Jonathan Forbes, Ashley Jensen. On Amazon, season 2 available Friday
Matthew Gilbert can be reached at gilbert@globe.com. Follow him on Twitter @MatthewGilbert.