The series focuses on the global law enforcement agency known as S.H.I.E.L.D., which was introduced in Phase One of the Marvel Cinematic Universe. (Iron Man, The Incredible Hulk, Iron Man 2, Thor, Captain America: The First Avenger, and The Avengers.) The series revolves around Agent Phil Coulson (Clark Gregg), who had seemingly died in The Avengers.
The first episode is directed by Joss Whedon, the director of The Avengers and the overseer of Marvel’s Cinematic Universe Phase Two, which kicked off with Iron Man 3.
As far as I know, there is no premier date for the series, as of yet. Have a look at the promo below: