Marcellin Pacaud, an old acquaintance of the commissioner, is killed under strange circumstances. The only clue left by the dead man is the mysterious number 189. Maigret puzzles over what it could mean ... Based on the 31st novel in the Maigret series: 'Mon ami Maigret' (1949). In the German-speaking world, the novel was published as 'Mein Freund Maigret'.