Two paintings are stolen. Amateur private detective Roland Gautier investigates.

Janvier, an embittered teacher, is fed up with his colorless, monotonous life. One day he breaks away and ends up becoming a circus clown. In his new world, he meets a beautiful acrobat nicknamed Lili and grows fonder and fonder of her every day of his life. The trouble is that the lady bestows her favors to two different lovers : wealthy married man Chardeuil and good-looking but listless young Antonio. He now considers his duty to make Lili recover her dignity.

A young intellectual, Hugo, joins the Communist Party out of a sense of idealism, only to see his principles manipulated by party leaders. He is given the assignment of killing Professor Hoederer, a party deviationist. However, he grows to admire the man and begins to have doubts about morals and revolutionary politics. But jealousy - Hugo thinks Hoederer has made love to his wife, Jessica - takes matters out of the political realm.

In a little town with a renowned college a female student is found after she was hogtied and strangled to death. Inspector Marco is assigned to catch the murderer.