S5, E3: From the terrifying future of the United Kingdom to one of the darkest chapters of its past - World War Two. The Doctor and Amy find themselves in a top-secret cabinet war room deep beneath the London streets. And there, gliding among the nicotine walls and Bakelite telephones, the Daleks are hatching their deadliest scheme yet. Only one man can help the Doctor - but whose side is Winston Churchill on?