Here’s Jimmy! After the mother of all cliff hangers – did Chuck really just burn himself to death? – gonzo Breaking Bad spin-off Better Call Saul (with comedy veteran Bob Odenkirk in the title role) has returned for a long-awaited fourth season. If you enjoy smart, heartbreaking TV you will be giddy with anticipation.

This much we knew going into the new run. Jimmy McGill, the slippin’, sliding corner-cutting lawyer who will eventually metastasise into Breaking Bad’s glib and amoral Saul Goodman, is mortally estranged from his older brother Chuck (Michael McKean).

And Chuck, whose irrational fear of electricity has been exposed to public ridicule by Jimmy, has apparently kicked over one of the gas-lamps used to illuminate his crazy-dude hermit shack. Is this the end for the character so grippingly played by the once and future David St Hubbins? (actually yes – it was confirmed over the summer Chuck has shuffled off to the great lawyers’ chambers in the sky).

Meanwhile Jimmy’s girlfriend Kim (Rhea Seehorn) has been forced to scale back her legal practice after nearly dying in an exhaustion-related car accident, and Saul’s future enforcer Mike Ehrmantraut (Jonathan Banks) is working for local gangster and sometime fast food magnate Gus Fring (Giancarlo Esposito).

Written down, it all suggests that Better Call Saul is a work of many moving parts. But, really, the series has a simple dramatic arc. Jimmy started out as a well-meaning, if flawed striver and will end up as shallow and callow enabler of evil drug lord Walter White – before fleeing the Breaking Bad shitshow for what he hopes is a quiet retirement managing a Cinnabon in Omaha, Nebraska (good luck with that “Gene”). The thrill and the tragedy is watching the humanity beaten out of McGill one blow at a time. Especially sobering is the realisation that Kim, in staying true to Jimmy, has set herself up for an unhappy ending.

“It is a horror story to some extent,” show-runner Peter Gould explained recently to the Hollywood Reporter. “You do know what’s coming, and you do know how deeply Kim has tied herself to Jimmy.”

The somewhat zany atmosphere of the first three seasons is dialled down significantly, it has been revealed. Jimmy is increasingly unlikeable while Mike’s duties for Gus Fring will usher the series explicitly into the noir milieu of Breaking Bad.

“We take our humour where we can find it, but this season, there are moments of darkness and intensity that rival anything we ever did on Breaking Bad,” Gilligan told Vulture. “Better Call Saul gets surprisingly dark. We’ve got Jimmy’s story, and now increasingly, we’ve got the pre–Walter White Breaking Bad, where Mike Ehrmantraut’s character gives us entrée to Gus Fring and to the world of the cartel-empire building that’s going on north and south of the border….

“Peter and I didn’t realise this at the start, it took us literally years to realise this, but the show is a tragedy. It’s a tragedy that Jimmy McGill ever turns into Saul Goodman. We hear fans say, ‘Well, does it really have to happen?’ We ourselves have said, ‘Does it actually have to happen?’ But it must. The show is called Better Call Saul.”

Better Call Saul will never, it feels safe to predict, have the cultural impact of Breaking Bad. That series, which debuted a decade ago, lit up the zeitgeist.

One reason is because it was so rich in metaphor. Walter White was an average dude kicked in the face by life – a tragic figure with whom it was easy to identify. A high school teacher forced to take a second job to pay the mortgage only to be then diagnosed with cancer…. here was a guy who had played it straight and ended up on the losing side. So he ripped up the rule-book and started over.

There was so much to unpack, were you inclined to delve deep. The defenestration of middle class life. How a midlife crisis can filter the shutters through which you observe the world. The tension between being the person your family want you to be and the person you know you need to be.

Better Call Saul is something else entirely – a Rockwellian portrait of an every-dude who, cheated by life, concludes that perhaps he should be the one doing the cheating instead. Hollywood always tells us to be true to who we really are. Better Call Saul tells us that this isn’t always a good idea.

“Mostly what we think about is how the hell does Jimmy McGill become Saul Goodman,” Gould said recently.

“Why? What possible motivation could you have for a law school graduate, maybe not the best law school, but he is a law school graduate who has accessed all sorts of legitimate ways of doing business… why does he become Saul Goodman? Is it just because he wants money?… We’re really trying to understand the character, and it makes us wonder exactly who Saul Goodman is.”

A new episode of Better Call Saul season four comes to Netflix every Tuesday.