Robert Plant on Amy Cook's It's Gonna Rain

Singer/Songwriter Amy Cook was working on her new album, laying down a vocal track with guest artist Patty Griffin when a voice from the control room chimed in:

Do you mind if I give it a go?

In Cook's words: "I did not mind."

When the person offering to lend a vocal to your new album is Robert Plant, who would mind.

He sang it a couple of times and it was perfect.

"It" is the Cook song, It's Gonna Rain, which will appear on Cook's new album, Summer Skin, due for release August 28th.

The track can be previewed on Rolling Stone's flash music player.