Saul Goodman burst into “Breaking Bad”’s second season fully formed, a sweaty shyster in a strip mall, a criminal lawyer with a motor-mouth that could save his life and a conscience up for sale. Over the next three years, we didn’t learn that much more about him; as Walter White descended to deeper levels of moral monstrosity and Jesse Pinkman tortured himself with guilt, Bob Odenkirk’s flamboyant lawyer remained largely the same: a lovable sleaze with fake hair and a fake name. (“The Jew thing I do for the homeboys,” he tells Walt in his first appearance. “They all want a pipe-hitting member of the tribe, so to speak.”)

Considering Saul’s static persona, it shouldn’t be surprising that Vince Gilligan and Peter Gould, the creative team behind “Breaking Bad” and now “Better Call Saul,” at one point considered spinning him off into a half-hour comedy. The Saul Goodman we knew was a perfect fit for the sitcom, a form that thrives on characters who are able to have adventures each episode and then return to the status quo.

Luckily, Gilligan and Gould have made “Better Call Saul” into something at once more interesting and more familiar: a mordantly comic origin story showing us how a small-time lawyer becomes the man with his face on a bus stop. By the third episode, it’s developed the same propulsive, addictive quality of its predecessor.

The premiere, which airs Sunday night (the second episode follows on Monday), begins with a melancholy prologue, a seven-minute silent film about Saul’s life post–“Breaking Bad” and post-Walt. But soon enough, we’re back in 2002, when Saul was still Jimmy McGill, a hustling Albuquerque public defender representing unsavory types for $700 a case. Like Walter White in his pre-Heisenberg days, Jimmy is a man desperate for respect. He works out of a tiny office in the back of a Vietnamese nail salon, where he checks his empty answering machine and sleeps on a pull-out-couch. Odenkirk is often placed in wide shots, dwarfed by his surroundings and thwarted by the world he encounters. Gilligan and Michelle MacLaren, who directs episode two, make poetry of life’s mundane indignities: broken coffee machines, indifferent parking attendants, condescending colleagues. 

And while Walt reacted to disrespect with curdled entitlement, the repressed anger of the man who believes he deserves more, Jimmy has the ambition of someone who’s always been treated like a screw-up. It makes for a gentler show. “Better Call Saul” isn’t necessarily more comedic than “Breaking Bad”—which could be pretty funny in its own right. But instead of its predecessor’s epic grandeur and sweeping statements about the toxic American dream, this new show plays in a minor key. By the time it kicks into gear in the second episode, “Better Call Saul” has the feel of a caper. Jimmy’s arc has some similarities to Walter White’s: an overlooked white guy is pulled into the criminal underworld as he tries to make use of his talent (just replace Walt’s chemistry skills with Jimmy’s gift for the gab). But like the show he now anchors, Jimmy’s ambitions are smaller—and we know his eventual descent will be less steep as well. 

Odenkirk has spent most of his career as a comic, but he’s fully able to carry a dramatic show on his shoulders, bringing a pathos to Jimmy/Saul’s madcap hustling. If only the characters around him were as fully realized. Mike Ehrmantraut (Jonathan Banks) is engaging as always, but has little to do. As Kim Wexler, a high-class lawyer who has a complicated history with Jimmy, Rhea Seahorn is a blank; she seems imported in from a summery USA original series, the disapproving blond love interest in a pencil skirt. Her colleague Howard Hamlin (Patrick Fabian) is even more nondescript. But Odenkirk meets his match in Michael McKean, playing Jimmy’s older brother Chuck. A former high-powered lawyer, Chuck now suffers from a mysterious—and possibly psychosomatic—illness that keeps him cooped up inside.

There were a lot of reasons to greet “Better Call Saul” with cynicism. Unable to convince Vince Gilligan to keep “Breaking Bad” running for another five seasons, AMC green-lights a spin-off in hopes it will become the next zombie hit—that’s the kind of mercenary decision a huckster like Saul Goodman would appreciate. But the show stands on its own, a hero’s journey with a seedy legal drama mixed in. It’s not “Breaking Bad,” at least not yet, but it passes the most important test for now: It’s very, very entertaining.