the ratification of the accords in Vienna, after which a bombing kills King T'Chaka of Wakanda. T'Chaka's son T'Challa vows to kill the bomber, who security footage indicates is Barnes. Despite Romanoff's objections, Rogers and Wilson track Barnes to his hideout in Bucharest and attempt to protect him from the police and T'Challa. Rogers, Wilson, Barnes, and T'Challa are captured. Barnes is soon released by Colonel Helmut Zemo, who uses HYDRA's trigger words to question Barnes about the 1991 mission, then sends him on a rampage. Rogers stops Barnes and sneaks him away; when he regains his senses, Barnes explains that Zemo is responsible, and that he is heading to the Siberian facility where Barnes was held, ostensibly to unfreeze the other Winter Soldiers the stolen serum was used to create.