The Murderer Lives at Number 21

Several crimes signed by a mysterious Mr. Durand are committed in Montmartre. A tip from a snitch leads Inspector Wens to the assassin's lodgings, a boarding-house at 21, rue des Lilas, where the policeman disguised as a pastor takes a room. The detective will have to be extremely quick-witted to deal with the lodgers at 21 as each in turn is accused and proven innocent. On top of everything else, he is hampered by his girlfriend Mila Malou's awkward affection and bumbling intervention as she is intent on solving the case herself.