Hugo leans into the light and dark motif he has made great use of and points out that it is in the deep shadows that Valjean and Cosette can take refuge. Where Javert had a group of 2 or 3 with him before, he now has 7 or 8, a group of soldiers have bene pulled into this endeavor.
They are moving up the street, slowly and systematically, checking every crevice and potential hiding spot. There will be no avoiding their search when they reach this part of the road. By Valjean’s calculations they have 15 minutes at most.
in the recesses of the wall, he looks for ways in, or up, over or through this wall and the building attached to it. Every attempt fails and time is running out. We find Valjean pushed to the edge, but there is no way he will abandon the child. As noted before, we are seeing the system repeatedly bear down on Valjean and Cosette - right at the time when they were finally enjoying some level of freedom and learning to love they find themselves hunted and trapped. There can be no peace it seems, as long as Valjean’s past is still hanging over them.