No, not a newly discovered movie by Alfred Hitchcock!
Compulsion is betrayal from within a person. It usually seems to be coming from outside a person, from some other will or force. It's very frightening.
A saying: "First the man takes a drink. Then the drink takes a drink. Then the drink takes the man."
Substitute any behavior for "takes a drink." Cut-throat business dealing. Seduction. Stealing. Overeating. Binging and purging. Gambling. Behavior repeatedly carried to an extreme that endangers or destroys self or others, alienates family and friends, causes loss of jobs. Behavior a person hides from those who are not part of it. Behavior a person hides from his or her own consciousness. Behavior a person has decided to change, then finds he or she does it again, against reason, against self-interest, against self-respect.
People experience compulsion in less dramatic ways, of course. The milk goes on the left side of the top shelf in a refrigerator. Always put both socks on before putting on a shoe. Habits make life convenient, saving the effort of perpetual decision-making. Habit has moved into compulsion when minor adaptations make us very uneasy; when finding the milk in the "wrong" spot can trigger a family argument.
Compulsion can be overcome with help.