Martin is about to go on vacation with his wife Ariane and his 4 month old daughter Cerise. It is then that he meets Constance, his ex, his childhood sweetheart, herself flanked by two children. It's decided: we will spend a few days together, in the sun, in the family home. Like the good old times. For better or for worse, between darling children, tense buddies and neurotic spouses. The troubles, the emotions, the feelings "of the old volcano that we thought were too old" were then reborn. The exes bite it, the others crack, and all drink.