Marius Vallois is twelve and needs a father. Marie Vallois has a twelve-year-old son, huge professional responsibilities, a demanding lover, a job vacancy to fill, a beloved sister, a complicated cousin but no father for Marius. Robert Pique has a steam iron, a pile of ironing to do, a Chinese fantasy and a neighbour whom he protects while looking for work. Monsieur Papa is the story of the strange bond that will be formed between these three characters. A bond that will give them plenty of headaches and mark their lives.