A Boy Falling Out of the Sky

M9, T15: Abby becomes disturbingly close to a mental breakdown as she copes with a multitude of problems, including her missing pilot brother and needy mother, Maggie (recurring guest star Sally Field). Meanwhile, Carter returns from Africa. Abby and Carter try vainly to keep a brain-dead boy alive a few minutes longer for the sake of his grieving parents. Weaver confronts a man who stole her purse. Pratt gets a big surprise after accompanying paramedics to the scene of a comatose homeless man on the street. Kovac arrives at the hospital in time to aid an overdosed teenager. And Lewis is flattered by a young cancer patient who admires her--but she must still deliver grim news.