The main character of the film, Dorellik, is a parody of the comic series Diabolik.

[2][3] Dorellik, an Italian contract killer who lives on the French Riviera accepts a job to kill everyone named Dupont in France for a rich customer who expects to receive a large inheritance.

How to Kill 400 Duponts was a film starring popular singer and television host Johnny Dorelli.

[1] Producer Dino De Laurentiis had been producing a film based on the Diabolik fumetti neri series and sued the producers of How to Kill 400 Duponts over their original title Dorellik, which led to the film being re-titled Arriva Dorellik (lit.

[4] Terry-Thomas, who played a starring role in Arriva Dorellik, also ended up guest-starring in De Laurentiis' Danger: Diabolik.