As told through flashbacks, the story is not believable. Elliott and Philby, both MI6 agents, are supposedly close friends of more than 20 years. Philby’s had been involved in communist-leaning groups at Cambridge and first wife (irl) was, it appears, a card-carrying communist. The notion that MI6 broadly and Elliott couldn’t figure out-for decades-that Philby was a double agent (much less allow him to rise almost to the highest position in MI6) beggars belief. The question is raised but not answered. Nor does the show even do a good job of showing a close friendship over decades that could have explained how Elliott was duped. Short flash backs are not convincing. The shows fails to address the only interesting question, which is how Philby- which is how was Philby, who was known to have communist leanings since college-able to rise to the top of MI6 while engaged in treason and espionage for more than 30 years.