Spooks (2002)

S5E9 The Criminal

MI5 is tasked with safeguarding Niko Grecic, the former associate of Tezlia, a Serbian on trial for war crimes. They are aware that Richard Dempsey, a former MI6 operative who betrayed them, is intent on eliminating Grecic before he can take the stand. Adam, Jo, and Zafar are determined to ensure Grecic's safety at all costs.