At the far end of the Grand Locos, a former train-repair depot-cum-main-exhibition-site for the 17th Lyon Biennale, there is a vast dark space. It takes your eyes a moment to adjust, but through the darkness you rapidly perceive a series of eight video screens, hung in a spiral formation, illuminating the space with an orange glow like fires in a cave. On each screen a person, holding aloft a flashlight, which illuminates the stalactites and the cave paintings that surround them. The figures begin to hum and trill different notes into the echoing chasm. Suddenly, a chord is struck, and the vibrations of their voices begin to fill the space like warm air. One by one, the filmed subjects sing. Different songs, different voices, different languages coalescing and harmonizing in a chorus that overwhelms you with waves of sound. You move through the space, spellbound by this sonorous butterfly garden. The notes flutter their little wings, enveloping you with something strange but familiar.