Hagar’s Song is often so lovely it’s unsettling. It pairs saxophonist/flutist Charles Lloyd with Jason Moran, the pianist for his already dulcet quartet (and the Kennedy Center’s jazz adviser). Without a rhythm section, the duo’s intimacy can make for awkward listening—like eavesdropping on an intensely private moment.

There’s no other way to describe “Bess, You Is My Woman Now,” from Porgy and Bess. Even without lyrics, Lloyd and Moran interact like the titular couple, trading parts and, in the final third, phrases. Still more revealing is the song’s opening: Porgy’s part, here played by Lloyd in a clear tenor tone that often sweeps into alto range. As he works the melody with only slight embellishment, Moran’s chords tenderly graze his sax line, embracing them as we’d expect Bess might while Porgy sings to her.

Something similar happens on the closing “God Only Knows”; Lloyd and Moran begin Brian Wilson’s song in a plaintive near-whisper that finds both playing the melody until settling just before the end into more traditional lead-and-accompaniment. It’s not just the ballads that offer such intimate moments. Ellington’s “Mood Indigo”—usually presented as a ballad—here appears as a midtempo swinger. Moran and especially Lloyd treat it as the blues that it is, with a vaguely carnal groove that’s among Moran’s specialties, and blue notes and growls from the sax. Even so, the two are sharing something profound. They improvise together in the song’s middle; as the second chorus begins, both instinctively quote the song’s opening, then venture out into atonality and back without missing a beat.

Not everything on Hagar’s Song is as exquisite, though. That’s foretold on “Pictogram,” a jagged free improvisation wedged in between ballads—a warning of thornier territory to come. Darkness falls with “Hagar’s Song,” an unrelentingly morose five-part suite, which explores Lloyd’s great-great-grandmother’s tumultuous life in slavery. If the rest of the album finds Moran and Lloyd sharing confidences, here they turn from each other to portray Hagar. Moran’s low-register plod on “Journey Up River” is tangential to Lloyd’s haunted bass-flute line: It’s mainly there for rhythmic momentum. The concert flute on “Alone” seems to weep while Moran focuses on a sinister vamp underneath; the pianist takes command on “Bolivar Blues” but soon concedes to Lloyd, whose alto darts fitfully against the piano’s nervous run. Only on the bittersweet “Hagar’s Lullaby” do they reclaim their mutual empathy, with Moran lovingly repeating Lloyd’s phrases back to him.

The album’s metamorphosis doesn’t last. After the suite, it moves to another swinger—Earl Hines’ “Rosetta”—where Lloyd’s tenor responds to Moran’s jump rhythms with a unique blend of sweetness and giddiness, then a painfully sensitive rendition of Bob Dylan’s “I Shall Be Released” on which even the accents the two hit together sound sympathetic. The structure presents questions of intent: Why was Hagar’s troubled story buried among sweet lyricisms? Is the former a nightmare, or the latter a blissful escape? They point to the scope of Lloyd and Moran’s achievement in Hagar’s Song—but like the album, the questions are unsettling.

Stream the record at ecmrecords.com.

The original version of this post misidentified the type of saxophone Charles Lloyd plays on “Mood Indigo.” He plays tenor sax, not alto.