The Passing

"The Passing will become the most important campaign in the Left 4 Dead story, as all the Survivors are being called together in one campaign."

- Doug Lombardi

The Passing is an upcoming DLC where the Left 4 Dead 2 Survivors meet up with the original Survivors from Left 4 Dead.

Players will still take on the role of the Left 4 Dead 2 Survivors as they meet up with the original four in a small town in Georgia somewhere between Dead Center and Dark Carnival.

The DLC will also add a new Uncommon Common Infected type and new weapons—one melee and one firearm. There's also "a new co-operative challenge mode of play." In addition to that new mode, the Passing will be playable in Survival, Versus and Scavenge modes.

Valve hasn't announced pricing details yet, but they do have a target release window: "early spring" for both the PC and Xbox 360 versions.