In her novel, Who is Julia? Barbara Harris invents the strange case of "Julia and Mary Frances." Mary Frances is out for a walk with her young child when suddenly the child breaks away and runs in front of a streetcar. Julia, who is nearby, sees what is about to transpire and throws herself in front of the the child, pushing her to safety. Unfortunately, a double tragedy ensues. Julia, in her effort to save the child, falls across the tracks and is crushed by the streetcar. Meanwhile, Mary Frances, fearing that her child will be hit, has a stroke and collapses on the sidewalk. Both women are clinically dead.

But just then, Dr. Matthews, a brilliant neurosurgeon, happens by. She directs the emergency workers to take the women to her nearby clinic where she performs a macabre procedure. While the trunk of Julia's body was crushed in the accident, her brain was untouched. Mary Frances, however, suffered irreparable brain damage though her body remained intact. Dr. Matthews decides that, for the sake of both, she will insert Julia's good brain into Mary Frances' good body.

The operation was a success. The question is, however, who is the person lying in the recovery room?