The minds of Billy Milligan (1981)

Subjected to horrific abuse at the hands of his stepfather, Billy Milligan "went to sleep" to protect himself from the pain. In his place other personalities rose: Ragan, the protector of children; Alan, the fast-talking con man; Christene, a cheerful innocent child; Adalana, a melancholy lesbian who yearned for love...twenty-four personalities in total. But when Billy is implicated in a series of rapes and abductions, it will take a devoted psychologist and a landmark trial to discover which personality is responsible, and uncover the dark past that created them.