Spooks (2002)

S7E2 Split Loyalties

Determined to seek vengeance, Harry sets out to dismantle the head of Russia's intelligence operations in the UK, collaborating with Lucas North. However, Lucas has secretly shifted his allegiance away from MI5 and manipulates Harry's trust. This betrayal leads to a Russian submarine launching an assault on Britain’s communication infrastructure, resulting in widespread financial turmoil and social disorder.