The Last Enemy

After living in seclusion in China for a few years, mathematician Stephen Ezard gets a culture shock when he returns home for his brother's funeral. England has been transformed into a national-security state, and the government wants his help to further expand its ability to monitor citizens. Stephen declines, but then a woman's strange disappearance makes him reconsider the offer.

Stephen's plan to lay low is foiled by a fire alarm, and he's abducted by a mysterious man demanding information. Fearful of being linked to Moreton's death, Stephen turns to Eleanor for help and later finds something he's been searching for.

Russell offers Stephen and Yasim a deal-he'll help them get answers if they help him find his daughter's killers. Stephen promises to use TIA to access data on the staff of Kellerman-Deloit, the manufacturer of the suspicious Hep B vaccine. Meanwhile, back at the flat, Michael is looking for Yasim and Nadir and determines to start his own investigation of Kellerman-Deloit.

The brothers have a tense reunion, with Michael demanding to know Yasim's whereabouts. Stephen goes to tell Yasim the news, but a security lapse compromises Russell's hideout. Michael explains his discoveries about the batch of disease-causing vaccine and enlists their help to find one of the refugees who received it.

Following the marketplace bombing, Stephen, Michael, and Yasim seek refuge, but the complicated relationships between them cause friction. To make matters worse, Michael grows sicker by the minute. Stephen volunteers to steal blood samples that may help save his brother, but what he discovers is more dangerous than he could ever have imagined.