officers, having Danny leave a disgraced officer also would be "one time too many" for a series that is meant to second guess the audience. In addition, Oyelowo did not want the "lingering thought" of a possible return. The producers wanted to use Danny's death as a powerful end to the series. "The Sleeper" sees the MI5 team in a different light, going to great lengths to get the sleeper agent, Fred Roberts, to do what they want him to do so that the producers can make the audience sympathise with the character, as well as despise the main characters on some level for their methods. There were other instances of the main character going through great lengths to solve the case, including Adam's interrogation methods, brinking on torture, in "Frequently Asked Questions". "Love and Death" sees Danny and Zoe ordered to carry out an assassination. Wolstencroft did not want to do it lightly, as he wanted somebody like Danny going through "something dreadful." He previously did it before with the death of Helen Flynn in "Looking After Our Own", but "Love and Death" did this in the point of view of the killer, not the victim. "Celebrity" introduces a new plot style, which does not involve terror threats. Brenton wrote it as a more light-hearted episode that saw the characters emmeshed in a world they cannot handle. Despite this, Collins stated that MI5 do other duties other than fighting terrorism, though they would not gain as much media attention. Penhale also stated MI5 in the episode are in a way protecting the country, as if a national icon is under threat, the country's morale could drop. "Who Guards the Guards?" and "Frequently Asked Questions" were considered for the second series, but because there was not room for them, the producers bumped the episodes back to the third series. Research and realism Although the series fictionalises the world of MI5, several storylines are based on truth. The series had advisors who were ex-MI5 officers. The producers wanted to use world events that Britain and America were directly or indirectly responsible for, where the consequences of an operation are worse than the problems they were intended to resolve, known as blowback. One example is the two powers aiding the Afghan Mujahideen in 1989 before pulling out of the country; this ultimately led to the rise of Al-Qaeda. Brenton modelled Fred Roberts