There are three missions
The "Raven Strike" DLC is composed of three missions: "Secure Dawn," "Cold Walker" and "Argent Thunder." And no, The Walking Dead fans, "Cold Walker" is not about zombies in the snow.
The first is an old school recon mission set in a swamp, the second has you infiltrating the Russian countryside, and the third takes place during a chaotic surge of violence in the heart of Moscow.
They're decently long and mechanically varied enough that they feel surprisingly fresh, running the gamut from full-on stealth to balls-out fire fights before they're done.