The Fifth Sally

Daniel Keyes, who studied psychopathology for a long time, spent many hours in psychiatric hospitals with specialists working with patients who had rare disorders. As a result, his novels emerged, which detail the most fragile, unpredictable, and interesting mechanism —... the human psyche.
The Fifth Sally, written two years before the famous Mysterious Case of Billy Milligan, tells the story of Sally Porter — a waitress from a New York restaurant. At first glance, she is an ordinary, unremarkable woman.
But, unbeknownst to Sally, there are four other women hidden within her. Nola — a cold intellectual artist, Derry — an irrepressible daredevil, Bella — a sexually obsessed failed actress and singer, and finally, Jinx — a potential murderer filled with rage and hatred. Every time Sally Porter finds herself in a difficult situation, she experiences a severe headache and loses consciousness.
That’s when one of her alters appears. If a handsome man shows up, Bella flutters onto the scene. If a problem arises that requires intellectual effort, Nola takes charge.
And if it's necessary to fend off an attacker, the merciless Jinx inevitably intervenes. Psychiatrist Roger Eshem faces a challenging task: to merge four different personalities to create the fifth Sally.