At 30 tracks, and featuring upwards of 40 guests, this rock album from one of country’s most famous and resonant voices all too often resembles a shaggy behemoth hell-bent on overkill. Bygones – an original composition – finds Parton alongside Rob Halford from Judas Priest and Mötley Crüe’s Nikki Sixx, the latter fighting Parton for the hairspray. An overegged cover of Let It Be ropes in not just Paul McCartney and Ringo Starr, but Peter Frampton and Mick Fleetwood too. Lead single World on Fire, on which Parton rails gutsily against society’s ills, promised much more substance. In among the hair metallers and big, blowsy hits are a slew of female-forward collaborations, often more pointed or playful. Parton’s duet with Debbie Harry on Heart of Glass is a welcome new wave interloper. A cover of Led Zeppelin’s Stairway to Heaven featuring Lizzo – and Sasha, her famous flute – is not just witty but inspired. You don’t have to strain too much, either, to hear a plausible feminist reworking of songs such as (I Can’t Get No) Satisfaction, when Parton joins larynxes with Pink and Brandi Carlile. But overall, Rockstar is both a savvy commercial package and a fudged artistic opportunity.