Tony Stark disappeared shortly after the Avengers started coming into their own. All traces led to dead ends, and time marched on. In the spring of 2017, it came to light that Hydra was deeply intertwined with SHIELD, and Captain America found out his best friend still lives. Now, James "Bucky" Barnes has come home, more or less. His mind is his own, including the fractured memories that flit just beyond his reach. A drop-in appearance by former SHIELD director Fury clarifies one thing: the Winter Soldier had met Tony Stark.
HYDRA need a replacement for Zola’s genius, and they have years worth of experience breaking and brainwashing a good man into something they can control.