Mercifully, this film doesn't include the song of the same name by the Rolling Stones, and coming from a person of Robert Guédiguian's staunch left-wing reputation I'd have been surprised (and very disappointed) if if had. No, Lady Jane comes from a tatoo of a marijuana leaf, with that name underneath: 'Mary Jane' (an old-fashioned name for marijuana) would perhaps have been more appropriate, but no matter.
The difference between this film and other Marseilles-based films by Guédiguian is that – although this is as usual about pals together – it's essentially a film noir: the three pals are (mostly) killers. There are two flashbacks which clue us in on the past, before the three – Muriel (Ariane Ascaride), François (Jean-Pierre Darroussin) and René (Gérard Meylan) felt obliged to go their separate ways. That was before the trio were into robbery (particularly fur coats), before Muriel killed a jeweller.
Now, Muriel has a boutique in Aix, François is in boat repair business, and René is a pimp with a striptease joint. They haven't met for years, until Muriel's son is kidnapped and a ransom demanded. So she meets her two former accomplices, they club together to pay the ransom, but that's not what was really wanted: the jeweller's young son had seen his father murdered (seeing the tatoo was the giveaway), and wanted Muriel to see what it feels like to have a loved one killed right in front of you.
In retaliation, the gang of course kidnap the former jeweller's son in turn, but already the trio has proved that violence merely begets violence, revenge is a one-way-street, so time for a rethink?