Dominic Sandbrook continues his exploration of the most innovative and imaginative of all genres with a look at science fiction's fascination with aliens. But what if we don't meet aliens in space and instead they come to earth - to conquer us?

Dominic and leading writers and film-makers look at science fiction's obsession with alien invasion, from all-out assault to sinister hidden threats, and how it has reflected real-life anxieties - whether they be the challenge to Victorian imperial power of HG Wells's War of the Worlds, the Cold War-era paranoia of Invasion of the Body Snatchers or more recent concerns about racism and immigration in District 9.

And we celebrate the most famous alien invaders of all - the Daleks.

Among the contributors are David Tennant and Steven Moffat (Doctor Who), Richard Dreyfuss (Close Encounters of the Third Kind), director Roland Emmerich (Independence Day) and special effects maestros Phil Tippett (Jurassic Park) and Doug Trumbull (Close Encounters).