This farce concerns the culprit in Lady Godard's murder. A certain detective makes it clear that Lady Godard was murdered by a member of her own family, despite their protests. Regrettably, the services of the detective's bodyguard are required. 
That's the only reason the murderer 
would do such a thing.
ذلك السبب الوحيد لإقدام
القاتل على شيءٍ كذاك
Das ist der einzig denkbare Anreiz dafür.
Esa es la única ventaja.
Esa es la única ventaja.
Voilà pourquoi
il a pris tant de précautions.
È l'unico vantaggio 
che riesco a individuare per tali azioni.
Essa é a única coisa
benéfica que vem disso.
Это единственная возможная причина.