Set in modern-day London, a group of radical activists take over an energy company’s annual gala and take 300 hostages in order to expose the hosts’ corruption. Their just cause is hijacked by an extremist within their ranks, who is willing to murder everyone in the building to send his anarchic message to the world. It is up to an ex-soldier turned window cleaner, played by Daisey Ridley, suspended 50 stories high outside the building, to save those trapped inside, including his younger brother.