Infamous: First Light is the newly announced DLC for Infamous: Second Son that allows players to return to the game's Seattle setting and play the origins story of Abigail "Fetch" Walker.
There's to be a Conduit Training Room where players can practice and post their best scores, and the whole thing will be standalone - you won't need a copy of Second Son to play it. Here's the description from press release:
"Unravel Fetch's dark past as she relives her troubled memories while being interrogated by Brooke Augustine in the notoriously harsh prison for superhumans - Curdun Cay."
"See Fetch develop her powers and become a trained killer, then fight to escape the maximum security facility and seek revenge against those who've wronged her."