Zombie Army 4: Dead War got its first story DLC today, the first in a three episode story called Hell Cult. This particular chapter, which is available now if you've got the Season Pass or bought the Deluxe Edition, is called Terror Lab.
Hell Cult, Terror Lab... that's the Zombie Army I know and love. "You and your fellow deadhunters must infiltrate a strange laboratory, tear your way through zombified researchers, and solve the mystery of why the dead continue to rise!" I'd hazard a guess that the "mystery solving" mentioned will involve shooting Nazi zombies.
This first episode also features a new playable character in the form of 'American Sea Captain' (his name is Josiah), a "classic Boris outfit" as well as new weapon bundles for a PPSH sub-machinegun and a M1 semi-auto carbine.
A roadmap for the game's first season of DLC has also been issued: April will see a new story episode called Blood Count, as well as a new Renegade Officer playable character and new "bloodsoaked weapon skins" (frankly ludicrous in a game with this much blood already in it). Then in May, another mission, then in summer (winter in Australia) there will be a new horde map, a new difficulty level and a new "Elite" mode (presumably it makes the game harder).
Full details on the roadmap are here. Check out a trailer for Terror Lab below: