She was granddaughter of Bess of Hardwick and, due to her mother's death when she was only seven, was largely raised by Bess. She was herself considered as a possible successor to Elizabeth as Queen. Catholics hoped she would marry an Italian. She wound up marrying William Seymour without the approval of King James VI (I). She and Seymour broke out of the Tower of London, tried to get out of England, missed their rendezvous, and had to flee separately. He made it, but she was captured just as her ship neared Calais. She went on a hunger strike and died in the Tower in 1615. Her Wikipedia article is here.