The haunting cover photo of the dishevelled sculptor Camille Claudel sets the conceptual tone for song-cycles by Jake Heggie that, for all their relative harmonic conservatism, expand what the medium can do to explore uncharted emotional territory. Yes, we can have Francis Poulenc and Wanda Landowska nattering back and forth about his delayed concerto in Friendly Persuasions. Numerous voices come and go during Pieces of 9/11. An instrumental interlude arrives near the end of Camille Claudel – a buffer when the piece changes channels from inner to outer dialogues.

The Claudel cycle, the strongest on the disc, has poet/librettist Gene Scheer stepping into the mind of the noted sculptor who was Auguste Rodin’s lover but spent her last 30 years in a mental institution. Joyce DiDonato is the voice of Claudel, articulately accounting for herself in the first person in a piece suggesting she retained keen powers of observation despite her illness. Whether in the conversational vocal lines or in the string quartet accompaniment, Heggie and Scheer explore the protagonist’s grief and alienation without heart-tugging sentimentality, even in the poignant final song when Claudel has a rare visitor. Though Heggie’s thematic ideas might seem a bit commonplace on first hearing, listeners are advised to stay alert to each song’s last note. Invariably, one is ambushed by the music’s cumulative effect.

Much of the rest is typically engaging mid-weight Heggie, with haunting near-quotations of the sea music from his celebrated Moby-Dick opera when the poems require something other-worldly. Performances by longtime Heggie collaborators definitely sweeten the package: DiDonato couldn’t be more dramatically on point as Claudel, Nathan Gunn exhibits deepening artistry amid the poetic abstraction of A Question of Light and Stephen Costello captures the high-traffic succession of personalities of Poulenc’s world in Friendly Persuasions. Each disc ends with short, light flute pieces played with customary artistry by Carol Wincenc.

Still, the set would make a stronger overall impression if consolidated into a single disc with nothing but top-drawer work by this composer, who is still in the process of introducing himself to the international opera community. I could have done without Pieces of 9/11: Memories from Houston, which tells us that after New Yorkers jumped to their deaths from the crumbling twin towers, a child was crying in Texas. A bit peripheral?