Once upon a time, total surveillance was the province of George Orwell and totalitarian states, but we now live in a world where oceans of data are gathered from us every day by the wondrous digital devices we have admitted to our homes and that we carry with us everywhere. At the same time, our governments want us to let them follow everything we do to root out evil before it can strike. If you have nothing to hide, do you really have nothing to fear?

In Who's Looking At You , novelist and occasional futurist Nick Harkaway argues surveillance has reached a new pitch of penetration and sophistication and we need to talk about it before it's too late.

This is our brave new world: data from pacemakers are used in criminal prosecutions as evidence, the former head of the CIA admits 'we kill people based on meta-data,' and scientists celebrate pulling a clear image of a face directly from a monkey's brain.

Where does it end, and what does it mean? Surveillance used to end at our front door, now not even the brain is beyond the prying eyes of an information-hungry world. The application of big data brings many benefits and has the potential to make us wealthier, keep us healthier and ensure we are safer - but only if we the citizens are in control.

The programme uses rich archive to illustrate how the 'watchers' have adapted to technology that has super-charged the opportunity to snoop. It examines the arguments of those who claim the right to keep their secrets while demanding that we the people give up more and more of ours. Transparency for the masses? Or simple necessity in a chaotic technological future? What happens to us, to our choices under the all-seeing eye? One thing is certain: if we don't make choices about surveillance, they will be made for us.