Lock No. 1

Cars drove past along with the trucks and trams, but by now Maigret had realised that they were not important. Whatever roared by like this along the road was not part of the landscape. ... What really counted was the lock, the hooting of the tugs, the stone crusher, the barges and the cranes, the two pilots' bars and especially the tall house where he could make out Ducrau's red chair framed by a window.

Maigret is drawn into the orbit of the self-made, mercurial Ducrau, as the latter's past catches up with him.