Tense drama series about the different challenges faced by the British Security Service as they work against the clock to safeguard the nation. The title is a popular colloquialism for spies, and the series follows the work of a group of MI5 officers based at the service's Thames House headquarters, in a highly secure suite of offices known as The Grid.

Cast:Peter Firth, Nicola Walker, Max Brown, Lara Pulver, William Hope, Alex Lanipekun,

Genre:Drama, Action & Adventure, Crime,

country:United Kingdom,

Production:BBC, Kudos,