Set in the current London, a group of radical activists takes over the annual gala of an energy company, taking 300 hostages to expose the corruption of the hosts. Its fair cause is kidnapped by an extremist inside its ranks, which is ready to kill everyone in the building to send its anarchic message to the world. It falls into a window cleaner in former soldier, played by Daisey Ridley, suspended 50 floors outside the building, to save those trapped inside, including his younger brother.