Cécile and Alain have been living together for twenty years. He runs a small hi-tech engineering company in Grenoble that is doing well – extremely well – and although she has no need to work, Cécile continues to teach at the local high school.
They are a wonderful, indestructible, model couple, to the great chagrin of their doctor friend, Georges, who is not insensitive to Cécile's charms.
Cécile has always been anxious by nature, but this time she is sure that Alain is hiding something from her.
He’s right to keep what’s troubling him hidden. If Cécile knew the truth she’d be distraught. Alain thinks he’s going to die. In a few days, Georges is going to operate just to make sure. No matter the diagnostic, Alain will then tell Cécile the truth. In the meantime, he doesn’t want her to worry needlessly.
Cécile only knows one thing: Alain is lying to her, and if he’s lying to her, then something is wrong, seriously wrong. She doesn’t know what it could be. Maybe he’s got a lover? If he wants to leave her, then that’s serious. Maybe he’s got problems at work? Like the difficult trial over a patent that he faced a few years back? If that’s the case, then, once again, they risk losing everything – and that’s serious. Cécile wants to know. She asks Pascal, the husband of her friend Agnès, to investigate. He’s a cop, it’s right up his alley. Pascal discovers that there is nothing to discover, everything is fine. Except for the fact that he has also fallen for beautiful Cécile’s charms. He would have preferred it if Alain were leading a double life, but it’s not a problem, Pascal will find something – or invent it.
Then again, he may not have to bother, for Alain has noticed that Cécile is seeing a man on the sly and that this man is following him. He’s afraid that his wife has a lover, a lover who wants to steal his patents. He’s afraid that she is the lover’s accomplice. No, his wife doesn’t have a lover, he is not seriously ill, nobody wants to steal anything from him, but it is too late, the wheels are already turning.