S2·E10 A Cage for Satan (2)

Another second parter to end the Series. Cyberax's destructive nature has entered Ros' brain and Beckett and Ed find themselves racing against time (and the fact that if Ros finds out about the true nature of Cyberax, her mind will explode) to save her. Beckett ‘foils' Jean-Daniel's plans, but in the process accidentally tells Ros the truth about Cyberax, and Ed has to kill her, electrocuting her. The reason being that ‘because Cyberax is a virus in the memory, you have to shut down the system and reboot with a completely new set of instructions'- (as said by Ed).