This is not the first concept album based around the original sin in the Garden of Eden. It’s not even the first one on Alpha Classics: soprano Anna Prohaska produced ‘Paradise Lost’ with pianist Julius Drake, clutching an apple (and a naked man) as the cover image (7/20). On ‘Forbidden Fruit’, Benjamin Appl’s album with regular collaborator James Baillieu, the baritone is pictured with a whole box of sweet treats, but he is the only Appl(e); there are grapes, a pear, a fig; most suggestively, out rolls a pomegranate, spilling its scarlet seeds. To eat or not?

Travelling across eras and genres, this is a diffuse collection capturing the erotic, the innocent and the corrupted. It works because of the intimacy of the performers (in a warmly confiding acoustic) and the palpable sense that the pair are in sync. Baillieu bookends the album with a piano solo version of ‘In Paradisum’ from Fauré’s Requiem, and it’s both heavenly and sickly. It is as much Baillieu’s work as a dramatist as Appl’s as narrator that pulls Fanny Hensel’s gothic fantasy ‘Die Nonne’ or Schubert’s familiar ‘Gretchen am Spinnrade’ into unusual focus. As the singer probes the respective heroines’ shame and neurosis, the driven quality to Baillieu’s playing ensures that ballads shiver with guilt. Less convincing are the pair’s brief spoken interludes, little postcard excerpts from Genesis 3 that teeter towards kitsch.

That said, the theme of seduction (and penitence) is not taken wholly seriously – just as well, as it would become suffocating. Appl does not always pretend that he is really gender-swapping: the little orgasmic gasp that he emits at the close of Poulenc’s ‘L’offrande’ casts the number as a caprice. In Grieg’s fascinatingly modernist ‘To a Devil’, Appl roguishly establishes that ‘I only care for devils / when the devils are like you’. These audible winks, however, don’t smudge the artful power of a number such as Debussy’s ‘La chevelure’ (Debussy apparently wanted a female virgin to premiere it), which concludes in post-coital despair.

It’s all delivered with wit, intelligence and sophistication, and the thematic joins don’t feel forced despite the breadth of the material. The move into the 20th century suggests a fertile new area for Appl, with Weill (‘Youkali’), Lothar Brühne’s ‘Can love be a sin’ or the caustic social critique of Eisler and Brecht’s ‘Die Ballade vom Paragraphen 218’, about the plight of a homeless, pregnant woman.

Where Appl leaves me wanting is in the body of his smooth, supple baritone. Sometimes it simply lacks enough weight to give a forceful enough line (Hahn’s classic ‘À Chloris’) or properly supported low notes (Richard Strauss’s ‘Der Rosenband’). The same shortcomings make the final number, the escape to transcendence of Mahler’s ‘Urlicht’, oddly underwhelming. It’s a case of needing less fruit and more fibre.