Season 10, Episode 3:

Trace amounts of radioactive material has been found at Heathrow Airport. Section D find that known anarchist Johnny Grier (Mel Raido) is in the city, who is believed to be making a dirty bomb in London. To get to him, Dimitri Levendis (Max Brown) is assigned to honeytrap his sister, Natalie (Georgina Rich), via Internet dating. Section D follows him to a cell, who plans to attack the Velanon Group, a financial company who made millions from a nuclear disaster. When Dimitri confronts him, Grier reveals he thought he was smuggling heroin to the country, and is not part of the bomb plot. Reluctantly he agrees to help; they find a van, only to find it empty; Grier double crossed them. He intends to assassinate Velanon's CEO using the radioactive powder. Dimitri fails to stop him, and the building is evacuated. Meanwhile, Towers offers Ruth a promotion to his security advisor, leaving the Grid and MI5. Harry's suspicion into Coaver has been solidified, especially after Calum found what Tariq found before his death; one of the muggers was also present during Gavrik's assassination attempt. Furthermore she is a deniable CIA asset.