Spooks (2002)

S8E5 Sudden Death

Harry is troubled by the unexpected passing of CIA director Samuel Walker. He firmly believes it wasn't a suicide, and when another CIA agent turns up dead, he starts to suspect a connection to the power summit taking place in Basel. Meanwhile, Ros is taken aback when her former mentor, Jack Coleville, reaches out to her, revealing that he has a role in the unfolding events.