Hangar 13 has released a new trailer for Mafia III which appears to set up the plot of the game, starting off with a heist. From here relationships are set up between different characters and factions, and there’s also quite a bit of action interspersed between how the characters relate to each other. If you want to avoid any SPOILERS though then I would advise not watching the trailer at all.
Mafia III launches on October 7th for PS4, Xbox One, and PC.
Source: Press Release