TV series
Reclusive mathematician Stephen Ezard returns to England after years in China, finds his brother's widow, and becomes entangled in a plot involving a new national database (TIA) and a terrorist scheme.
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Checked Sep 3, 2026
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Reclusive mathematician Stephen Ezard returns to England after years in China, finds his brother's widow, and becomes entangled in a plot involving a new national database (TIA) and a terrorist scheme.
Choose an episode, then use the watch options above for the show.
Episode 1
Stephen Ezard returns home from China for his brother's funeral and finds himself drawn into an intrigue when he tries to determine the circumstances of his death.
Directed by Iain B. MacDonaldWritten by Peter BerryGuest stars Christopher Fulford, Alina Șerban, Tom Fisher, James Lance, San Shella, Ovidiu Niculescu, Shiv Grewal, Noma Dumezweni
Episode 2
Stephen continues his search for Yasim as two groups track his movements, TIA marketing intensifies at Parliament, and an unexpected illegal debarks at the port.
Directed by Iain B. MacDonaldWritten by Peter BerryGuest stars Christopher Fulford, Rupert Procter, Tom Fisher, James Lance, San Shella, David Calder, Nicholas Sidi, Inika Leigh Wright
Episode 3
Russell saves Yasim and Stephen against his better judgment, the government becomes suspicious of Stephen, an unexpected player joins the game.
Directed by Iain B. MacDonaldWritten by Peter BerryGuest stars Christopher Fulford, Alina Șerban, Rupert Procter, Ovidiu Niculescu, David Calder, Emil Hostina, Claudiu Istodor, Nicola Stapleton
Episode 4
Stephen deals with a rival for Yasim's affections and sudden homelessness after his identity is removed from the database.
Directed by Iain B. MacDonaldWritten by Peter BerryGuest stars Christopher Fulford, Alina Șerban, Rupert Procter, San Shella, Ovidiu Niculescu, Chipo Chung, Paul Higgins, Emil Hostina
Episode 5
As Stephen finally pieces together the conspiracy, Michael's illness worsens and another moves to tie up all the loose ends.
Directed by Iain B. MacDonaldWritten by Peter BerryGuest stars Alina Șerban, Rupert Procter, Inika Leigh Wright, Paul Higgins, Kieran O'Brien, Daniel Williams, Grant Davis, Robyn Isaac
Episode information updated Sep 16, 2026
Benedict CumberbatchStephen Ezard
Anamaria MarincaYasim Anwar
Max BeesleyMichael Ezard
Robert CarlyleDavid Russell
Eva BirthistleEleanor Brooke
Geraldine JamesBarbara Turney
David HarewoodPatrick Nye
Alex CaanHaman
BBC OneUnited Kingdom
Castel FilmRomania
BBCUnited Kingdom
GBHUnited States
