The Falcon and the Winter Soldier cast puts two fan-favourite supporting characters front and centre, along with Baron Zemo, a villain that Marvel fans have already seen on screen before. Zemo isn't just any supervillain — he's one who's terrifyingly familiar to both Sam Wilson and Bucky Barnes from his past run-in with the Avengers.
Baron Zemo, aka Helmut Zemo, is the main villain in Captain America: Civil War, which starts out as a philosophical conflict between the Avengers and quickly turns personal. His motivations are simple: his family was killed in Sokovia, so he wants revenge on the Avengers. Zemo is personally responsible for putting Bucky at the heart of the conflict: he tracks down Bucky's old HYDRA handler and steals a book of trigger phrases, then plants evidence to make it look like Barnes is the bomber who carries out the attack that kills Wakandan King T'Chaka, among others.
When Bucky is apprehended and taken in for questioning — despite Steve and Sam's attempts to protect him — Zemo impersonates a police psychiatrist in order to get an interview with Bucky. During that interview, he casually but deliberately invokes the series of trigger phrases from the HYDRA book, despite Bucky's pleas for him to stop. As a result, Bucky's "Winter Soldier" persona is reactivated and is forced, by Zemo, to carry out another rampage through the building in order to give Zemo time to escape. This time, Steve has better luck and is able to get Bucky out; when Bucky wakes up, he's back to himself again and reveals three things: how the triggers worked, that Zemo is the real bomber, and that Zemo is trying to track down a base in Siberia where several more brainwashed, cryo-stored "Winter Soldiers" are being kept.
At first, it seems like this might be the start of a truce, but when Steve and Bucky reach Siberia — followed by Tony Stark, who figures out that Bucky was framed — they learn that Zemo has already killed all the other supersoldiers. Zemo then carries out his real goal: destroying the ties that bind the Avengers. He shows Tony a video that reveals that Bucky, while brainwashed as the Winter Soldier, was the assassin who killed Tony's parents decades ago. As the heroes fight each other, Zemo slips away, planning to die by suicide now that he's fulfiled his mission of revenge. He's unexpectedly stopped by T'Challa, who has been tracking all of this to avenge his own father's death and who turn Zemo over to the authorities.
The last time we saw Zemo, he was being imprisoned for his crimes, but clearly he's found a way to rejoin the action. It's not clear what he's been up to in the years since, but what is clear is that he's going to be a very dangerous threat. The action will be very personal for our two heroes when The Falcon and the Winter Soldier debuts on Disney+ on March 19!