"Orphan Black " has been one of the stealth surprises of the year. If you haven't caught up with this twisty BBC America thriller , in which Tatiana Maslany brilliantly plays a set of clones , you should try to get up to speed.

On Saturday, BBC America is airing every episode of the drama during an all-day marathon, which will be capped by the Season 1 finale. Check out HuffPost TV's exclusive clip from the finale above.

It may take "Orphan Black" a little time to engage fully in the clone conspiracy that envelops the lead character, a tough grifter named Sarah Manning, but it's worth sticking with the early episodes. As it gains steam, Sarah has to cope with a series of the mysteries and conundrums as she attempts to steal the life -- and the job -- of a dead cop who looked exactly like her.

As the first season progresses -- and trust me, it quickly becomes highly addictive -- Maslany effortlessly establishes distinct personalities for Sarah and all her "sisters": There's the pot-smoking, nerdy scientist, Cosima; the prim, fussy suburbanite Alison; and the wild-card religious nut Helena, each of whom gets her own compelling arc.

The supporting cast features standouts like Jordan Gavaris , who plays Sarah's divinely bitchy brother Felix with sensitivity and flair; Maria Doyle Kennedy, who plays Felix and Sarah's former foster mother; and Matt Frewer, who plays a messianic scientist. Given scenery to chew, Gavaris and Frewer happily munch on it, but they also give their characters depth, texture and, in Felix's case, pathos. He and Sarah grew up with a foster mother and endured chaotic lives, and Maslany and Gavaris make the fierce bond between the often cynical siblings absolutely believable. Kennedy's character is a cipher at first, but soon becomes a key player in Sarah's journey.

"Orphan Black," which has already been renewed for a second season , has evolved into something that is equal parts techno-thriller, neo-noir and yuppie satire; it's both gritty and escapist, and it wisely treads lightly around questions of nature, nurture and identity. The goal is to entertain, and the episode in which foul-mouthed Sarah had to pretend to be uptight Alison during a suburban pot-luck dinner was one of the funniest and most entertainingly twisted hours of TV I've seen all year (there are moments with a glue gun you won't soon forget). In the hands of lesser writers, "Orphan Black" might have asked obvious or overly pretentious questions about why these women turned out so differently, but the show allows its serious ideas to sneak in around the edges, rather than drag the whole enterprise down.

The occasional contrivance and convenience pops up as Season 1 headed into the home stretch, and Sarah's ex kept turning up like a bad (and uninteresting) penny, but those are minor quibbles. "Orphan Black" makes its central premise about illegal cloning not just realistic but emotionally satisfying: Sarah had gone through life assuming she was alone and combatively keeping most people at a distance, but in the course of this zig-zagging tale, the former orphan begins to form bonds that tie her more closely to life -- a life that is in more danger every day.

There's no question that Maslany is giving not just one, but several of the year's finest television performances. Each clone is completely distinct, right down to body language and gestures, and the actress switches among accents flawlessly. And playing one clone who's imitating a different clone and somehow getting that imitative quality exactly right? Those are some next-level skills right there.

"Orphan Black" is a very promising addition to the ranks of smart, female-centered action-adventure and mystery dramas that have proliferated of late. The complicated ladies of "Hunted," "Continuum," "Bletchley Circle, "Lost Girl," "Top of the Lake" and "Defiance" are not to be trifled with, and Sarah and her sisters fit right in.

For more on "Orphan Black," check out this primer from my colleague Chris Jancelewicz, which includes interviews with the cast, and read his recent interview with Gavaris .

The "Orphan Black" marathon begins at 12 p.m. ET on Saturday, June 1 on BBC America, and the season finale airs at 9 p.m. ET on Saturday, June 1 on BBC America.