Frank Perry is an institutionalized convict fourteen years into a life sentence without parole. When his estranged daughter falls ill, he is determined to make peace with her before it's too late. He develops an ingenious escape plan, and recruits a dysfunctional band of escapists - misfits with unique skills required for their daring plan and united by desire to escape their hell hole of an existence. Much of the action takes place within the tunnels, sewers and underground rivers of subterranean London.