Complex sentence: At the ending of the previous episode, CeCe (then unknown) kidnaps Alison and takes her to Radley Sanitarium, where she recounts her story to Alison, while the Liars assist through a live feed in a vault at the Carissimi Group.
Split into simpler sentences: At the ending of the previous episode, CeCe (then unknown) abducts Alison and takes her to Radley Sanitarium, where she recounts her story to Ali. Meanwhile, the Liars assist through a live feed in a vault at the Carissimi Group.