Cause and XS

With Barry out of contact in the Speed Force, XS witnesses Cicada kill Killer Frost and tries to travel back in time to stop the outcome... and a different teammate dies with her every attempt.

The Flash

Season Number: 5

Episode Number: 14

Episode Title: Cause and XS

Air Date: Feb 12, 2019

Source: The.Flash.2014.S05E14.1080p.HDTV.x264-LucidTV