What a Shitty Day!

This is an important day for Marc Chanois, an insurance advisor heading toward middle age: it's his fiancee Sabine's birthday, her parents arrive in Paris and Marc will meet them for dinner to announce the engagement (her father can't stand him), he's bought Sabine a Spitfire, and his most important client is to sign a policy. But, as the day wears on, he's vexed by an incompetent secretary, the unexpected return of a girlfriend he hasn't seen in five years, squatters who use his office at night, the jealous former lover of a flight attendant who lives in the building, and his boss's unexpected return from a Swiss clinic. Will he reach Sabine in one piece?