The series takes place in the fictional town Clerville and stars the titular Diabolik, initially represented as a ruthless and cruel thief who does not hesitate to murder anyone in order to accomplish his deeds, aided by his partner and lover Eva Kant. Over the time, the character evolved his personality, developing healthy roots and ethical principles such as honor, the sense of friendship and gratitude, and respect for noble souls, robbing and killing other criminals. Throughout his adventures, he is pursued mainly by the Inspector Ginko.