Paul Cazavel, a successful and seemingly healthy Parisian architect, learns from his doctor one morning, after a presumably routine checkup, that he has lung cancer. The doctor's prognosis is that he has at best six months to live. At thirty-nine, Paul feels betrayed and cheated, but can't indulge in self-pity on a day he has to spend breaking the tragic news to the people he thought meant everything to him.

There's his "best" friend, who, it turns out, is too busy with his own career to sympathize with Paul's dire disclosure; a mistress so carried away by her own grief that she forgets her lover's existence; a wife whose joy at the news of her husband's impending death shimmers through her cynical show of devotion. What has Paul been doing all his life? And who are all these insufferable people surrounding him? Paul has no time to keep up appearances. Under the gun of an inexorable deadline, he does exactly as he pleases, leaves his boring job, abandons his family, finds and pursues the only woman he really ever loved but had never dared commit to. His death liberates his life - for a while.

But nothing goes according to plan in a novel in which the unexpected is the order of the day.