The album cover of Isobel Campbell and Mark Lanegan’s “Ballad of the Broken Seas” reveals the record’s plot. In what could be a missing scene from “True Romance,” Campbell fixes her hair before a mirror in a cheap motel while Lanegan half-reclines on the bed, reading a book. As semi-tragic lovers on the run, Campbell and Lanegan are more than convincing; their contrasting vocals teem with feeling and suggest a deep chemistry. Unfortunately, the songwriting generally fails to match their performances. The love story of “Ballad of the Broken Seas” suggests timelessness, but cannot achieve that height.

Campbell, a vocalist and cellist for Belle & Sebastian before going solo in the mid-nineties, wrote most of the album’s songs with Lanegan in mind after the ex-Screaming Trees frontman and sometime Queens of the Stone Age collaborator suggested they record together. Both artists have certainly achieved musical success in others’ projects (Campbell on Belle & Sebastian’s “If You’re Feeling Sinister” and Lanegan with Josh Homme’s Queens of the Stone Age). Lanegan is also known for Screaming Trees’ 1992 hit “Nearly Lost You” (one of the better ubiquitous grunge songs on alt-rock radio from Seattle indie bands’ major label debuts). Yet neither Campbell, whose ethereally wispy yet soulful voice would garner her the label of chanteuse if only she sang three registers lower, nor Lanegan, whose gruff bar-band vocals instantly evoke Tom Waits, have achieved even modest recognition in their solo work.

“Ballad of the Broken Seas” could, perhaps, change that. The title track — the album’s best — is a wonderful showcase not only for the pair’s vocals, but also Campbell’s cello, which takes over the melody halfway through. The best use of their dichotomous vocals, though, is also the most colorful — “The False Husband” is intermittently dark and sweet, accenting the strings and percussion with slight horns and a bell.

Another standout track, a cover of Hank Williams’ 1955 single “Ramblin’ Man” is right at home among the twelve 1950s country-inspired tracks. Here, as is predominant throughout, Campbell sings smoldering backup harmonies to smooth the edges of Lanegan’s lead. The song eschews the harp and strings of the other songs, relying more heavily on the twanging guitar. Campbell has said this skillful cover would fit well in a Quentin Tarantino film.

But like Tarantino’s own overreliance on his influences, Campbell’s sometimes derivative arrangements often sound uninspired at best. Early country music was, historically, driven heavily by singles rather than LPs; were this not the case, most of the tracks on “Ballad of the Broken Seas” may well have been covers of those imaginary records’ deepest tracks.

This feeling is heightened by the inclusion of two boring near-instrumental tracks: “It’s Hard to Kill a Bad Thing” and “Dusty Wreath.” The latter, at least, with its a music-box tone and position as penultimate track, serves to accentuate and introduce the closer, “The Circus Is Leaving Town,” the closest the album gets to a Tom Waits nod. The former, “It’s Hard To Kill a Bad Thing,” is much worse — it could even be imagined on a “Selections from New Age Guitar” album.

On the upside, Campbell and Lanegan’s distinctive and capably intertwined vocals often overshadow otherwise imitative songs (as suggested by the fact that the worst songs mostly lack vocals). When the lyrics of the opener “Deus Ibi Est” require an extra syllable to fit the rhythm, Lanegan sells “lend, oh” as perhaps no one else could. The lyrics’ framing of the album’s love story also helps listeners forgive the overly familiar melodies.

Overall, “Ballad of the Broken Seas” is best if taken as an album of covers. The striking and dramatic performances of sometimes-mediocre songs are probably not enough to prevent this album from becoming ultimately forgettable. Yet Campbell and Lanegan are certainly singular talents, something quite evident here. Though Campbell can’t freshly re-imagine her musical influences as well as Tarantino can his cinematic ones, her effort is hardly wasted.