Swedish vocal trio Erato had been singing together for a long time as part of a larger choir, when one night they sat down at the kitchen table and recorded a video. Within three days, almost 100,000 people had watched them perform Robyn’s Call Your Girlfriend, using only their voices and empty cottage cheese containers. By now, nearly five million have watched the video. When Robyn herself, the Guardian and Perez Hilton all wrote about them, it was the start of a career in harmony. Now Amanda Wikström, Ebba Lovisa Andersson and Petra Brohäll are recording their own songs.