Season 3, Episode 6: Persephone
What seems like a routine operation against Turkish mafia gun-running turns into something far darker when three of the mafia terrorists are shot by another gang member. One of the men killed was an undercover police officer. Zoe, the MI5 officer infiltrating the Turkish gang, finds herself on trial for conspiracy to murder. But did she order the killing? And even if she did, shouldn't her actions be defendable given the amorality of these terrorists? The jury must decide. Despite a deal struck between Harry and the Government, Zoe is sentenced to 10 years in prison. Outraged that she should be made a scapegoat, MI5 arranges for a stooge to take her place in prison and for Zoe to take up a new life and identity in Chile. Although it means losing his best friend, Danny has to persuade her to go. Zoe apologizes to Will, explains she is in some trouble but promises to be in touch. Then she disappears.
Read the recap for this episode here.