Given the critical and creative success of “Mr. Robot,” one would be forgiven for hoping USA’s next high-profile offering, the sci-fi drama “Colony,” would be similarly bracing and mold-breaking. “Colony” does have a few things going for it, most notably “Lost” veteran Josh Holloway as the patriarch of a family in post-invasion Los Angeles. But in general, this series is frustratingly patchy and generic — unwilling to grapple in any consistent way with the moral and political implications of its premise — and key elements of the story remain disappointingly underdeveloped. Pride of place is given to characters and relationships that don’t have much depth, despite the efforts of a capable cast and occasionally arresting action scenes. Like an alien shape-shifter, “Colony” keeps trying to morph into a fairly standard cop show with some espionage elements. In a stumbling effort to create enigmatic mysteries, it just ends up being vague.

Who are the aliens and what do they want? Good questions, neither of which is addressed in the first six installments of the 10-episode debut season. Viewers are dropped into the story about a year after mysterious visitors arrived on Earth; the only signs of them are the gigantic walls they’ve built around a populace that is now without cars for personal use, and lacks many other necessities. The Los Angeles “block” is separated into two areas: A Green Zone in the hills for the ruling class of collaborating humans, and a tightly controlled set of neighborhoods in “the flats” for workers, like Holloway’s character, Will Bowman. Movement is restricted, and a ferocious army of red-hatted human soldiers keep the peace for the Earthling leaders and the alien rulers — whose agenda and appearance are only a few of the things “Colony” chooses not to reveal or even hint at.

Sci-fi chronicles, especially when they’re serialized on television, live or die on their world-building abilities, and those set among the humans of modern-day Earth have to be both familiar and alien. That’s not easy to pull off, and much sci-fi fare aimed at the mainstream flounders because creatives don’t want their stories to seem too weird or off-putting, and end up sanding off all the edges. That didn’t happen with “The Man in the High Castle,” which, despite a few bland characters, remained watchable due its detailed alternative vision of North America, which gave the drama a palpable sense of mystery and menace. And while “The Leftovers” is very different from “High Castle,” it, too, created an altered world that gave meaning and context to the characters’ sometimes extreme actions: In the science-fiction realm, the depth of the storytelling is often reliant on the depth of commitment to the creation of a singular and intriguing alternative vision for humanity.

But the elements in the rather bland society depicted by “Colony” just don’t quite add up. Alien drones roam the city at will, and viewers are supposed to believe that all aspects of civilization and communication are monitored and tightly controlled. But resistance cells meet up regularly, obtain weapons and stage operations without major impediments, and plaster posters all around the city without much difficulty. A pirate broadcast by an underground leader named Geronimo gains listeners for months — but the entities who took over the world with apparent ease somehow can’t figure out where it’s coming from. For all the hype about them, the intruders clearly haven’t nailed the whole “immensely powerful alien overlords” theme that the show keeps hammering home.

Perhaps the strangest thing about “Colony” is that it’s not very strange: People play in parks, go to bars and talk about shortages without appearing to be inconvenienced by them all that often. An atmosphere of danger crops up occasionally, especially when the thuggish red hats are on the scene, but in general, the tone of “Colony” is much more serene and untroubled than it should be. For a population allegedly under constant surveillance by omnipotent aliens, daily life and routine subversion just seem too easy and commonplace. This isn’t the false calm of a frightened society — for the most part, it’s just L.A. with very few cars and lots of bikes (hey, that doesn’t sound too bad).

The superficiality and inconsistencies of “Colony’s” world might be less noticeable if the characters were deeper and richer, but they’re not terribly compelling, despite the divided loyalties the show plants early on. The drama keeps trying to prove that Will, a former soldier pressed into service by the repressive regime, cares deeply for his wife, Katie (Sarah Wayne Callies). But showing the couple kissing a lot and having sex is not a substitute for memorable and specific character development. And as is the case with Sullivan Stapleton on “Blindspot,” Holloway’s gift for wry comedy largely goes to waste here. It’s not that “Colony” should be a laugh riot, but Holloway’s so good at melding tough-guy energy and lackadaisical charm that it’s a shame he doesn’t get to use the latter more often. (Carl Weathers plays Holloway’s cop partner, a theoretically inspired pairing that should yield far greater results than it does.)

A lynchpin of the series — which viewers learn in the opening minutes — is that one of the Bowman’s three children was separated from them during “the arrival,” during which many others lost their lives. Both parents take big chances in order to find and bring home their son, but, like the aliens, the missing child remains off screen, unknown and therefore hard to invest in.

The political allegories are more apparent, given that the privileged live in the Green Zone (a name that recalls the Iraq War and its missteps), and the highly armed red hats carry echoes of the debate about America’s increasingly militarized police. Even darker elements are hinted at: Those who disobey are shipped off to “the factory,” which is never seen, but is presumably not a health spa. One episode opens with scenes shot from the helmet camera of an on-duty red hat — a well-deployed gambit that the episode soon sets aside in favor of more conventional storytelling. That’s a disappointingly frequent occurrence on this show, which is efficient at plot mechanics but frequently lacks deeper urgency. For instance, one character is referred to as a “true believer” — but of what?

There are explosions and tense sequences here and there, yet the focus on cops tracking down leads and on an unexceptional core family (with its inevitably boring teen character) keeps bringing “Colony” back to a much more conventional place. When all is said and done, the most memorable scenes of the first six episodes don’t involve family life or shootouts. They feature fine performances from Kathy Baker, Kathleen Rose Perkins, Peter Jacobson and Holloway, as their characters debate what it means to collaborate and survive in a post-democratic, possibly post-human world. Jacobson is brilliant in his role as the puppet leader installed by the new overlords, and the nuanced scenes of him explaining himself — and trying to convince himself that his compromises have been justified — are excellent.

USA has evolved beyond its former “blue skies” approach, which is a smart way to remain competitive in a world saturated in scripted TV. But if “Colony’s” skies get a bit darker, and if its characters deepen and delve more deeply into the moral complexities that surround them, the network eventually might have a worthy new arrival on its hands.