There are a lot of coincidences in Les Misérables that seem far-fetched, like Valjean landing in the one place where someone would recognize him as M. Madeleine and help him. Hugo treats them as divine design, referring at one point to “chance, that is to say, providence…”
My favorite is when Montparnasse tries to mug Jean Valjean outside Mabeuf’s garden while Gavroche is hiding in the bushes. None of the characters know each other at this point.
Another good one: Javert doesn’t normally read the news, but he picks up a newspaper for coverage of a special occasion on the very day that a tiny article appears about Valjean’s apparent death.