WHAT IT’S ABOUT Harlee Santos (Jennifer Lopez) is a corrupt NYPD detective in a Brooklyn precinct, supervised by an even more corrupt boss, Lt. Matt Wozniak (Ray Liotta). She’s an outrageous rule-breaker, as rookie Michael Loman (Dayo Okeniyi) quickly discovers, but then so are her colleagues, including Marcus Tufo (Hampton Fluker) and Tess Nazario (Drea de Matteo). As corruptible as Harlee is, she still wants to be a good mom to her 16-year-old, Cristina (Sarah Jeffery). And then, oily FBI special agent Robert Stahl (Warren Kole) comes knocking.

MY SAY Barry Levinson directs the first couple of “Blue” episodes, so you can make the reasonable assumption that they’re not bad. They’re not, although the second (next week’s) improves on Thursday’s opener. Lopez — initially stagy and little too blow-dried for her own good — gets better too.

But you may still wish to proceed with caution. Here’s one reason why: Lopez is an executive producer on this series, and while there are exceptions, rare is the watchable prime-time series with a star who also doubles as boss.

Another may be Lopez herself. As a glam judge on “American Idol” one night and butt-kicking cop on this the next, she and her handlers probably envisioned some delicious new form of synergy. (“Look at JLo! She can do it all!”) Or maybe they simply saw “Shades” as a convenient exit ramp from the waning “Idol.” That’s fine, but it doesn’t take into account viewers who risk mental whiplash making the transition from one role to the other.

But let’s say they do make this awkward transition. Any pleasant surprises herein? Sure. Foremost, “Shades of Blue” is not “Gigli” and — go ahead, admit it — you were secretly hoping this was going to be an epic disaster. We all need a good laugh.

The cast is uniformly good, too. Liotta occasionally goes full wacko here, recalling Henry Hill from “Goodfellas” or his character from “Something Wild.” Who doesn’t love that?

Meanwhile, Lopez and Harlee: There’s even a hint of real promise here as well, which may be the nicest surprise of them all.

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BOTTOM LINE Get past the tough-to-buy setup of the premiere, and “Shades” improves. The star? Initially tough to buy, too, but also improves.