For a couple of days this week, a Southern California hilltop was alive with the sound of — mystery.

Hikers venturing to Topanga Lookout in the Santa Monica Mountains found a battered upright piano, sitting on a graffiti-scrawled concrete slab with a panoramic view over the mountains between Calabasas and the Pacific Ocean.

Turns out, the piano was used for a music video by Seattle-based artist Rachel Wong.

The cinematographer, Michael Flotron, says he and four others used a dolly and rope to haul the 350-pound instrument a mile up the trail on Tuesday.

After the shoot, it was too dark to get the piano back down.

Flotron says people seem happy to leave it there — but if necessary, he'll haul the piano back down.