When the Tomorrow People learn the truth about the serum they were injected with, Stephen and Cara attempt to buy time for Jedikiah while he tries to create a possible antidote.

Growing impatient, Russell and the other rogue Tomorrow People make a rash decision to sacrifice Roger (guest star Jeffrey Pierce) to Ultra for their own safety.

RELATED | The Tomorrow People Episode 21 “Kill Switch” Guide

Check out the sneak peek images for "Kill Switch" (airing on April 28) in the gallery below: