The opening episode of the tense new Starz sci-fi drama Counterpart left me undecided for a long time, I must admit, on whether I wanted to stick around and figure it out.

Then at the very end, Howard Silk (J.K. Simmons) places the needle of his record player on James Carr’s “Dark End of the Street” and eases himself into a comfortable living room chair to sit back and just listen.

And I decided yeah, I’ll take a ride with Counterpart, which launches Sunday at 8 p.m. ET.

The sci-fi tentpole of Counterpart, harking back to Fringe and any number of other supernatural dramas, is that there are two parallel worlds and some version of us exists in each.

In that other world, we might be a very different person. We might also face great danger, which is why a secret United Nations agency called the Office of Interchange (OI) guards the passageway between the worlds.

Howard Silk has worked for that agency for 29 years. He reports for work each day and seems to spend his time pretty much in isolation, doing tasks whose purpose and value he does not understand. No advanced degree in sci-fi coding is required to say he is a cipher, a small cog in a big machine.

This seems to have gradually worn on him, a frustration compounded because his wife Emily (Olivia Williams, left) was in some sort of terrible accident and has spent the last six weeks comatose in a hospital bed.

Emily’s brother Eric (Jamie Bamber), on behalf of Emily’s mother, is pressuring Howard to sign release papers that would enable Emily’s family to take her back to her native England, where Howard might or might not ever see her again.

While Howard didn’t major in assertiveness, all this has pushed him to ask his OI boss Peter Quayle (Harry Lloyd) for a promotion to a position where he might get a little more involved in whatever OI actually does.

Be careful what you wish for, Howard.

Peter says no chance. But by coincidence, or perhaps not, Peter very shortly finds himself unexpectedly forced to give Howard a crash briefing when Howard’s wife becomes a target for an assassin.

The other world is involved, though it’s not immediately clear how. All we know is that suddenly there’s another Howard, or rather, another physical Howard, with strong indications he’s linked to doubles of other people as well.

Much is unclear here. What’s not unclear is that these crossover folks and the agency that tries to control them both play hardball. A lithe young woman named Baldwin (Sara Serraiocco) shows up with a gun and becomes a person of great interest to Aldrich (Ulrich Thomsen), the director of operations at OI. His team also has guns, and no one seems reluctant to employ them.

This makes Counterpart sound like a war-of-the-worlds kind of supernatural thriller, and that seems to be part of its mission.

But it also has a parallel ambition of its own, exploring the nature of humanity, of regret and loss, of love and trust. You know, stuff like that.

Now yes, all good sci-fi deals with greater issues in its own metaphoric ways. Counterpart, which has already been commissioned for two 10-episode seasons, seems inclined to address them more overtly, as reflected in the time it spends showing that its characters behave in ways we associate with regular old humans.

Howard, not alone, has private emotions and makes small everyday gestures that emphasize the ordinary nuances of his life. Those are not, at least in the early stages of Counterpart, subsumed by the show’s apocalyptic secret or its potential consequences.

At the dark end of the street, as James Carr reminds us, sometimes there’s just you and me.