Bluegrass music may never be the next big thing, but in the hands of neo-Americana artists Cadillac Sky it rings with truth, emotional depth and rootsy enthusiasm sure to interest Iron & Wine, Alison Krauss or Gram Parsons fans. On Cadillac Sky’s third release, Letters to the Deep, the acoustic quintet maintains an analog-aligned mannerism accented by mandolin, banjo, violin and harmony vocals, but push bluegrass in fresh directions.

Romantic disintegration ode “Trash Bag” balances back porch piano and uneasy fiddle with water-stained regret. Bright Eyes-esque “Bathsheeba” rollicks with turbulent twang and indie rock velocity. Standouts include rueful folk tune “Tired Old Phrases,” about the choices we repeat; “Ballad of Restored Confidence,” a country-appliqued appeal for a different destiny; and toughened tumbler “Trapped Under the Ice,” which transits from rustic to discordant rock.

Producer Dan Auerbach (the Black Keys) applies an offhand process that emphasizes minimal overdubs and first-take intimacy, which provides an instinctive stimulation.

Grade: B

Letters in the Deep is currently available.