Earlier this year, former Band of Skulls bassist Emma Richardson was painting in her London studio when the phone rang. It was producer Tom Dalgety with a rather urgent matter to discuss. He was working on a new record with the Pixes, and they had an all-too-familiar problem to solve: They’d just parted ways with yet another bass player, their third, and had to fill the spot, quickly. Was she interested?

“The call came totally out of the blue and was an incredible surprise,” Richardson tells Rolling Stone. “I had stopped making music,...