the other band members asked tarja to leave the group in 2005 after their "end of an era" tour. tuomas wrote an open letter to her, stating the reasons why she had to leave. he then put the letter on the official website. in 2007, swedish singer anette olzon became the new singer, and nightwish released a single, 'amaranth'. a few months later, they released the album 'dark passion play'.