Les Mis question
As far as Thernardier knows (or thinks), Valjean was in the sewers that night doing the same thing that Thernardier was doing: stealing from dead bodies. This kind of information, if made known in Marius' social circles, would destroy his reputation since he's marrying Valjean's daughter. So the Thernardiers do think it is a big deal that could ruin Marius' wedding day, and their plan is to make him pay for the information, and probably then to blackmail him in order to keep it quiet. And as ...