In the fall of 1994, 15-year-old Simon went to the convenience store and never came back. The next day, the body of the teenager is fished out of the river. 27 years later, his younger sister Élise tries to understand why he threw himself off the bridge. Helped by Philippe, a charismatic pastoral animator who led Simon's self-help group, she discovers that everything is always more complex than it seems.
A retired public figure and history professor begins to lose his memory and must learn to be more discreet as he expresses himself.