Complex sentence: Captain America is then branded a fugitive from S.H.I.E.L.D., and Rumlow's team is tasked with capturing and killing the captain and Black Widow, who discover that Pierce and Rumlow's S.T.R.I.K.E. unit are members of the terrorist organization Hydra.
Split into simpler sentences: Captain America is then branded a fugitive from S.H.I.E.L.D., and Rumlow's team is tasked with capturing and killing the captain and Black Widow. Cap's team eventually discover that Pierce and Rumlow's S.T.R.I.K.E. unit are members of the terrorist organization Hydra.