We already knew ahead of time, but Square Enix has today officially announced the first Deus Ex: Human Revolution DLC, Missing Link. Set during the three days in which Adam Jensen disappeared off the grid, it details how he was tortured by Belltower forces and fought his way to freedom.
The content allows players to rebuild Jensen from scratch, and features new narrative, new characters, and fresh levels. It's out in October and you can get your first look at the screens, as well as a hot trailer, in this very post. That's convenient!