schwab, and by the pritzker military foundation on behalf of the pritzker military museum and librarye rosalind p. walter foundation, damon button, craig newmark philanthropies, roger and susan hertog, cheryl cohen effron and blair effron, al and kathy hubbard. corporate funding is provided by stephens, inc. and by pfizer inc. [bright music] - sheila johnson, welcome to "firing line." - thank you so much. this is an honor. - you recently published your memoir. - yes. - "walk through fire: a memoir of love, loss, and triumph." the book starts with you as a 16-year-old girl coming home to the harsh reality that your father, who is a neurosurgeon, your mother, who is an accountant, decided to split up. it was your father's decision. and this, as you write, is a pivotal early moment in your life that shapes you. - absolutely. - [margaret] how? - i had to grow up real fast. i had to take charge of the family. my mother, she just had a complete mental breakdown. and it was a case where my father being one of eight african american neurosurgeons in the country, highly esteemed, my mother, i