Benedict Cumberbatch and Robert Carlyle head an all-star cast in a dynamic new thriller about a man whose search for the truth about his brother’s death catapults him into an international conspiracy – and a passionate love affair.

Authored by acclaimed screenwriter Peter Berry, the five-part contemporary drama co-stars Max Beesley, Anamaria Marinca, David Harewood and Geraldine James.

When the reclusive Stephen Ezard returns to London for the funeral of his brother Michael, an aid worker killed by a landmine, he feels like a stranger in his own country.

He finds a world that has changed subtly but significantly from the one he left – biometric ID cards are compulsory, passenger profiling at all major transport hubs is common practice, public spaces are monitored 24 hours a day by digital cameras and armed police patrol the streets.

Stephen flees to Michael’s flat, but he is shocked to find a desperately sick woman there, tended to by Yasim – who introduces herself as Michael’s wife. When the woman, Nadir, dies, Stephen and Yasim connect through their anger and sorrow and sleep together.

The next morning, Stephen is called to a meeting with a company called Inquirendo, who offer to fund his research in return for his public backing of their new project, TIA (Total Information Awareness), a super-database which will enable the government to perform searching background checks on suspects, trace their movements and profile citizens to detect likely future threats.

Stephen declines their offer and races back to the flat to see Yasim. However, to his horror, she has vanished and the flat is spotless.

Later, old flame and government minister Eleanor Brooke turns up in a bid to persuade Stephen to support TIA, and Stephen wonders if the database could help him find Yasim.

Someone else is interested in Stephen too – the menacing David Russell. And watching Russell are three high-level security personnel, led by Turney, with a big secret to hide.

Sunday 17 February
9.00-10.25pm BBC ONE