Is it cheating to set your show to the work of Nina Simone? And not just any old Nina Simone, but a selection that includes numbers from her legendary 1976 Montreux concert, in which she chastised the audience and argued with the songs, her voice mumbling then soaring. As every choreographer knows, great music can do the emotional heavy lifting for you, but you have to know how to handle it, how to give the music space, to meet its vulnerability and its virtuosity with the bodies on stage. Mathieu Geffré and his company Rendez-Vous Dance have the right instincts. What Songs May Do... is a duet for two men, Oliver Chapman and Paolo Pisarra, wearing smart shirts and natty moustaches, who move with the torrent of Simone’s piano as much as the sentiment of a lyric, the song is a third partner in a relationship that already looks like the ultimate “it’s complicated” situation. There’s an awestruck nature about the couple as Simone sings Someone to Watch Over Me; Marry Me sees sweet snapshots of domesticity; and they’re frantic and languorous within a single phrase to match the haunted hunger and desire of Wild Is the Wind. The dance swings between combative and conciliatory as the couple retread old cycles, and Geffré paces their journey well. There’s an elegance to their movement but also heft; they’re very solidly “people” in front of us, not just “dancers”. You become acutely aware of the space between the two men’s bodies. At first it’s a tiny motion: one torso concave; the other convex in response. But by the time they’ve unbuttoned each other’s shirts it’s one body pushing the air out of the way, the other sucked into the vacuum, or perhaps the repelling poles of two magnets, not quite able to meet. Geffré clearly knows what songs can do. But what dance may do is give a song another story, make a decades’ old recording come alive again right in front of you, with a twist. When Simone plays Feelings, a song she can never quite finish with its new chapters and false endings, that’s the relationship we’re watching right there. At Assembly @ Dance Base, Edinburgh, until 11 August All our Edinburgh festival reviews