Fans attending D23 were treated to this teaser for the final season of Marvel's Agents of S.H.I.E.L.D. It's a flash-back to 1931 where team of Chronicoms appear on a mysterious mission.
Agents of S.H.I.E.L.D. is the first and longest-running TV series produced by Marvel Studios, having started its run in 2013. Spinning out of the the Marvel Cinematic Universe, S.H.I.E.L.D. restarts the career of Agent Phil Coulson (Clark Gregg), miraculously revived after the events of Marvel's The Avengers, as he tries to pull together a task force of operatives that initially include Agent Melinda May (Ming-Na Wen), Agent Grant Ward (Brett Dalton), sci-ops agents Fitz (Iain De Caestecker) and Simmons (Elizabeth Henstridge) and new recruit Daisy 'Skye' Johnson (Chloe Bennet).
Bolstered by walk-ons from the characters such as Nick Fury (Samuel L. Jackson), Maria Hill (Cobie Smulders) and Lady Sif (Jaimie Alexander) and crossovers with Captain America: The Winder Soldier, AoS clearly established its connection to the larger MCU. Over time, numerous characters from the Marvel library have appeared such as Deathlok, Ghost Rider and Mockingbird to name a few.
