Beyond The Walls of Sleep
It started with a portal, a battle for humanity, an empty coffin at Tony Stark's funeral.
(It started with a portal, a bomb that never detonated, an act of self sacrifice that was futile.)
Then a distress signal. A last ditch covert-op. A recon mission with little hope of success.
(Then a Chitauri cell. A plague ship. Isolation.)
Four years too late they bring Tony home.