Equus (1977)

Psychiatrist Martin Dysart (Richard Burton) investigates the savage blinding of six horses with a metal spike in a stable in Hampshire, England. The atrocity was committed by an unassuming seventeen-year-old stable boy named Alan Strang (Peter Firth), the only son of an opinionated but inwardly-timid father and a genteel, religious mother. As Dysart exposes the truths behind the boy's demons, he finds himself face-to-face with his own.