In this BBC TV series, mathematician Stephen Ezard (Benedict Cumberbatch) returns home from China for his brother's funeral but finds himself caught up in two simultaneous stories of high level espionage. In one subplot, he aids (and romances) his brother's widow as she tries to determine the cause of a mysterious disease that the government wishes to cover up. In the other, he helps his exgirlfriend (now a politician) as she tries to convince the government to adopt "T.I.A.", a computerized system that will keep track of the whereabouts and activities of every individual in Britain.
In the first episode, quite a bit is said about the protagonist's mathematics. He is described as the famous author of Ezard's Theorem, the youngest Fields Medalist, and a likely recipient of the Nobel Prize. He is annoyed that people associate his work in statistics to killer bees. And, he gives a talk at the company developing T.I.A. on his geometry research, which sounds suspiciously like Hamilton's program to prove the Poincare Conjecture. (He accepts the company's offer to fund his pure math research in exchange for his work on T.I.A., but presumably he was more motivated by his desire to use their program to locate his brother's widow.)
Ezard is presented as the stereotypical, antisocial mathematician. He moved to China to avoid having to deal with people. His abrupt and condescending mannerisms are seen as a benefit to the company as it tries to use him to force the government to adopt T.I.A. officially. And, he appears to be obsessive about washing his hands, though, given the fact that a woman dies of a mysterious and possibly dangerous disease in his apartment, this may not be as crazy as one might otherwise think! Two characters mention that Ezard always wears the same outfit (as did Einstein, according to the anecdote, in order to avoid wasting time thinking of what to wear), though in the show he begins wearing other clothes when tracers are put into his own. Finally, it is Ezard who eventually figures out the solution to the mystery.
Thanks to Kevin Nooney who originally brought this work of fiction to my attention and wrote the following description, which was here before I had a chance to see the show myself.
Contributed by
Kevin Nooney
He definitely and unambiguously is a mathematician, though as the plot progresses, it is his programming skills that become more and more stressed. There are several scenes in the early episodes that specifically mention his mathematical work and one in particular that includes his presentation to two members of a company that is involved in developing the database tracking software that is at the heart of the plot. There is also a very brief deleted scene in which he talks about soapbubble geometry.

