Closed Circuit (2013) on Netflix

Plot summary

Farroukh Erdogan, a Turkish immigrant, faces charges as the leader of the cell behind the Borough Market bombing in London, which killed 120 people. Because the case touches national security, it proceeds under closed material procedures. Martin Rose is appointed to argue Erdogan's defense in the public trial, while Claudia Simmons-Howe serves as special advocate, viewing the government's secret evidence in closed sessions and putting Erdogan's interests there, with the judge ruling what Martin may use in open court. Martin and Claudia are former lovers whose affair ended his marriage. Once she has seen the confidential material the two are forbidden any contact, since it would compromise the trial. MI5 officer Nazrul Sharma delivers that material and monitors her.