Robert Plant and Alison Krauss’ “Raise the Roof” is an intense conversation between two friends who’ve sat at this table before, hashing out the blues. For all of its familiarity, this fresh chat – no less profound than their initial exchange, 2007’s autumnal “Raising Sand” – is a more sublimely otherworldly one, something warm and friendly, but with a celestial chill that didn’t exist during their first long talk. Here, and maybe even more so than on Plant, Krauss and producer T Bone Burnett’s first work from 14 years ago, these earthen blues, country and folk ghost tales — sung as luscious love (and hate) songs — are gifted with unearthly atmospheres, and more than a hint of premonition to go with the joy of reunion.

With that, “Raise the Roof” is all instinct, dread and memory rolled in a ball of silt, skronk, malleted drums and yawning pedal steel – a Dust Bowl Super Bowl where two talky, dynamic, nuanced vocalists exhaust and exalt each other. Maybe the terrain between them here is too familiar, its temperature mostly at a steady boil, and not enough chances get taken. But whether derived from folk and blues classicists, more recent writers (e.g., Calexico’s Joey Burns) or as new originals (Plant and Burnett’s co-write, “High and Lonesome”), both vocalists sound keen to outdo themselves while elevating their harmonies, literal and figurative, to new heights.

Led Zeppelin’s growly lion and the soprano mistress of modern bluegrass hit the ground running on “Raise the Roof,” but with a soft step, moving through the tall grass of undulating rhythm, on the flickering “Quattro (World Drifts In)” — the Calexico cover — with a gossamer-spun joint vocal that never jumps one hair above Burnett’s calming, desert-inspired vibe.

On “Raising Sand,” Plant and Krauss showed off their mastery over the Everly Brothers (“Gone Gone Gone”) and Allen Toussaint (“Fortune Teller”), so repeating those same tricks again here, on “The Price of Love” and “Trouble with My Lover,” respectively, is another sip from the heady brew of harmony and inventive rhythm… innovative drum and percussion curation being one of Burnett’s calling cards. Rather than use the Everlys’ familiar hiccup as the melodic hook to “Price of Love,” though, Krauss and her harmony partner use a descending chord’s suppler hum to lasso the listener. Then Burnett and percussionist Jay Bellerose grab you with a stairstep’s pulse as menacing as Krauss’ threat.

The quickly pit-pattering rhythm of “Trouble with My Lover” propels Krauss’s cattiest croon through the cool of Plant’s boyish blue harmonies and Marc Ribot’s watery baritone guitar lines. Ribot and Bill Frisell – his fellow atmospheric jazz-bo guitarist on “Raise the Roof” – act as nature’s elements, be it the fiery Santa Ana winds of “Go Your Way,” the azure liquid of “Trouble with My Lover” or the rainstormy bossa-rockabilly of “Can’t Let Go.”

Plant kicks up his heels on the not-so-mannish boy-like “Searching for My Love,” and the giddy “Can’t Let Go.” Think of the wild spirit that guided his 1984 project, “The Honeydrippers: Volume One,” covering R&B and doo-wop classics of yore. Plant takes that inspiration and reigns it in, make it less over-the-top on these “Raise the Roof” tracks. His vocals here are dryer and slyer, with Krauss pulling up the righteous rocking rear. Plant, the vocalist, may stretch out, ruminate and roam over the fatalistic lyrics of Ola Belle Reed’s salty blue “You Led Me to the Wrong,” but his real zeal and prickle comes through when put through quicker paces.

The churning-combine tone and slapped-face percussion on Bert Jansch’s “It Don’t Bother Me” sound hauntingly like Bowie’s “Lazarus.” Riff borrowing aside, such a somber ooze as Jansch’s eerie persistence gives Krauss’ cocky vocal phrasing a place to land. Something similar occurs to ardent accompaniment of Ribot’s banjo, and Stuart Duncan’s stringed mix of fiddle, mandolin and cello on “Last Kind Words Blues.” On a song penned by 1930s blues singer Geeshie Wiley, Krauss finds the eye of that quiet storm, and keys into its jazzier phrases, while never losing sight of its folksy blue grit. That she pulls Plant’s harmonies along, deep into its gently jazzy winds, must have reminded the lemon squeezer of his love of Joni Mitchell and all things “Going to California.” Gorgeous.

Plant’s serpent-and-vine-will-she-still-be-mine “High and Lonesome” – filled with the whirr of a bass accordion and an hypnotic Mellotron – benefits from the same cosmopolitan jazz-folk of Mitchell’s while also managing a foot in the crusty rock of his past. Such Zep-like self-expression comes before a solo Krauss’ most traditional country ballad on the album, “Going Where the Lonely Go,” from Merle Haggard and Dean Holloway. It’s a nice touch having penultimate songs such as these point to each singer’s origin story.

Ending with a droning desert rocker such as Brenda Burns’ “Somebody Was Watching Over Me” gives the ensemble cast a chance to sizzle, a place where “my strength was put to the test, and my weakness put to rest,” as the song goes. While Jeff Taylor’s stride piano bounces behind them (as does a burly background vocal courtesy Lucinda Williams), Plant and Krauss slither between each other’s vocal phrases – not so much like seasoned boxers in a ring, but elegant fencers wielding the weapons in recherché swordplay. While a little less grace and a little more grit could have benefitted their second pairing, Robert Plant and Allison Krauss’ “Raise the Roof” is nice and rough in all the right places.