Life is going well for Marie. She and her husband, Laurent, live a comfortable life in a large apartment in the eleventh arrondissement in Paris. Laurent has a good job at a big law firm and Marie enjoys her work at a bank, where she feels appreciated by her clients and colleagues.

Comfortable and secure, and ready for family life, the couple begin to try for a baby. But not long afterwards Marie experiences a shocking encounter which threatens to derail their plans completely, and her world slowly starts to fall apart.

Less than two years later, the family's apartment is cordoned off by police tape as forensic officers examine a horrific scene in the family apartment. Three bodies around a dining table. Marie, Laurent and their little toddler, Thomas, in his high chair. All three of them have been poisoned by Marie.