Marius wanders the streets of Paris wishing that he were dead, since his beloved Cosette has disappeared and he doesn't know if they'll ever see each other again. And he's in luck, because this is a very easy day to get yourself dead in Paris. You know, with the people revolting and everything.
On the way to the ABC Society's barricade, Marius finds himself thinking about his father's heroic acts in battle. Whenever he's not thinking about Cosette, that is.
When he finally finds the barricade, Marius heads inside without too much trouble. The dude's pretty much a zombie at this point, since he cares so little about being alive.