At the age of 12, Marianne Aya Omac was given an important gift: a copy of Joan Baez’s Live in Europe. On the streets of her native Montpelier, France, Omac sang and sang and sang, spreading a fire that started with Baez’s initial spark. Eventually, Baez herself heard Omac’s powerful voice, and this year, she brings the young folksinger to the States. Baez and Omac make a joint appearance on Monday, Sept. 12, at 142 Throckmorton. 142 Throckmorton, Mill Valley. 7:30pm. $28–$40. 415.383.9600.