Maigret, Lognon and the Gangsters

In book 39 of the new Penguin Maigret, the inspector learns that his hapless colleague Lognon is being menaced by some notorious American mobsters, and he makes it his mission to bring them to justice - despite threatening warnings that he is out of his depth.

This story has been published in a previous translation as Inspector Maigret and the Killers.