News reports discuss the growth in international terrorism because a willingness to negotiate with terrorists and offer concessions that give terrorist organizations perceived legitimacy. American Special Forces recently made a disastrous attempt to free 52 hostages in Iran. Meanwhile in the United Kingdom, Margaret Thatcher continues to push controversial economic and social reforms during her first year in office. A banker's holiday approaches in London.Day 1. On April 30, 1980, six Iranian Arabs from the Democratic Revolutionary Front for the Liberation of Arabistan storm the Iranian Embassy located at 16 Princes Gate, Kensington in London and hold at least 26 hostages inside. The terrorists chain the gates shut. BBC reporter Katie Adie (Abbie Cornish) is stopped by police going to the Iranian Embassy to check on her colleagues who went to the embassy to get visas that day. She witnessed Salim (Ben Turner), the leader of the terrorists inside, stand on a balcony and demand everyone step back and his desire to talk with a negotiator.At that time Lance Corporal Rusty Firmin (Jamie Bell) is training with other SAS agents on rescuing hostages when his group leader Roy (Emun Elliott) is paged. The 22 Special Air Service Regiment prepares for action. They are transported to London from Hereford immediately.Max Vernon (Mark Strong) is the Chief Inspector Metropolitan Police Negotiators Unit. Vernon enters the Montessori Nursery School, seven doors away from the Iranian Embassy. A woman (Marjan Gorgani) is translating the demands from the terrorists. Salim demands the release of 91 Arab prisoners in Iran, or else they will kill a hostage at noon the following day. Deputy Police Commissioner John Dellow (Martin Shaw) and Tom Lovett (Matt Sutherland) greet Vernon. They disclose that PC Trevor Lock (Toby Leach) is among the hostages and perhaps still armed. They show him the standard field telephone used for communication which allows them to listen in on the terrorists within the Embassy if the telephone is not hung up.The BBC broadcasts the story of the terrorists on the evening news. They pinpoint the location and decry guns in British streets. Katie Adie is the field reporter on the scene. She eats dinner with her camera man Bill (Martin Hancock) in a car. He tells Katie the terrorists called the BBC to air their demands. Katie wonders what Margaret Thatcher will be willing to concede to the terrorists.High command meets late that night in Cabinet Office Briefing Room A on Whitehall Street with Secretary William Whitelaw (Tim Pigott-Smith) presiding. Whitelaw insists that British law will be followed. Whitelaw learns that the Iranians refuse to release anyone from jail and that Colonel Mike Rose (Robert Portal) of the SAS has quickly drawn up an assault plan that will likely be bloody. Early in the morning, the SAS squad arrives and seeks to avoid the press by going undercover as cleaners. They enter the Royal College of General Practitioners which is located directly next to the embassy.On Day 2, Max Vernon readies himself and kisses his wife Betty (Mia Blake) as he leaves home before daylight for a day of negotiations. A radio reports discusses that the police remain in charge of the situation but few details have been disclosed to the general public. The newspaper reports that the Iranians have blamed the West for the situation. The negotiators are frustrated that the terrorists called the BBC and the press is aware of the terrorists demands. There is the belief they cannot be successful negotiating through the press. The SAS team prepares to storm the building just before noon despite a lack of intelligence about the situation they face. The terrorists call the negotiator's desk. The negotiators try to tell the terrorists that Teheran is considering their demands but learn that the terrorists have already called Teheran. The Iranians have told the hostages they are welcomed as martyrs to the great Islamic State of Iran. The SAS establish a mobile command post directly behind the embassy with Major Hector Gullan (Colin Moy) in charge. Gullan has his team at the door fifteen minutes from breaching the embassy.Max Vernon negotiates with Salim by phone, saying that Max will help him by any means to avoid violence. Max explains that his government has no ability to force the Iranian government to do what is does not want to do. A gunshot is heard. Salim releases one hostage due to illness. The hostage warns the police not to enter the building as the terrorists are "armed to the teeth." The SAS is told to stand down.Max delivers food to the terrorist at the front door of the embassy. His family is able to watch his actions on television. With Vernon's calm negotiation skills on display, Salim reluctantly agrees to extend the deadline by 48 hours, demanding safe passage to Heathrow Airport on busses accompanied by ambassadors from the Arab League. Reporters say that the polices' soft approach will hopefully lead to a non-violent conclusion.Meanwhile, the SAS learn that many of the rooms in the embassy have been wired with explosives. Each terrorist possesses at least one fragmenting grenade. Bricks are removed, holes are drilled and microphone listening devices are introduced stealthily into the embassy. The SAS learns that at least some hostages are being held on the second floor. The team strategizes different methods of assault. Rusty Firmin suggests that the start their operation on the roof, enter the building through the top floor windows, secure the hostages inside the stronghold, and fight their way down from there. The team realizes this is the best plan they have.On Day 3. Vernon and his assistant review photos of the hostages when Salim calls and reiterates their demands. Gullan devises a new plan where the hostages and terrorists are provided a bus and transported to Heathrow. There the SAS team plans to rescue the hostages from the bus. The team is taken off site to rehearse the assault and discovers great risks to their own personal safety. News reporter Katie Adie notices the team being trucked off the site and reports to the public that the military is in place working alongside the police. While the media reports on the lack of police contact with hostages and speculates on the effectiveness of the negotiation methods employed, the SAS team continues to drill on the bus assault to gain control in less than six seconds.Then it is decided that no bus will be provided for the terrorists and they will not be transported to Heathrow Airport comparing the failed attempt of the Germans at the Munich Olympics hostage situation. Colonel Rose points out that the SAS team has never operated on English soil and that the job asked of them to perform a rescue in a stronghold is fraught with risk.Meanwhile the Arab League has agreed to help with negotiations but the Prime Minister insists that the United Kingdom will not be seen as a soft target for terrorists. British law will be upheld and the terrorists will never leave the country. Max believes they must offer the terrorists something tangible in hopes the terrorists feel they have achieved something and give up.Members of the SAS team climb onto the roof of the embassy to further plan their assault. They see thehostages through the skylight. The passage allows for a perfect opportunity for a distraction charge that Roy will deliver. Roy promotes Rusty to be the leader of the team and gives him the mission codes.Rose describes a plan to the political leadership where the SAS team enters through the skylight under the cover of darkness and neutralizes the terrorists as they sleep. The politicians are aghast that the SAS will be labeled an assassination squad. Though Whitelaw agrees to take the plan to the Prime Minister, he believes it will ultimately be up to the negotiators to break the deadlock or else the SAS will have to storm the building.On Day 4, outside BBC report Katie Adie debates with press writer Jimmy (Tim Downie) whether the army will attack the building. Inside, a dispute arises amongst the terrorists. Faisal (Aymen Hamdouchi) wants the prove their resolve. Salim agrees that they will kill a hostage if their demands are not met that day.Max learns that the Arab League refuses to be part of the negotiation if the terrorists are not allowed safe passage out of the UK, something the British government will never allow. Roy gets Firmin's promotion to team leadership approve by Gullan. Salim calls again, demanding to speak with the ambassadors. Max stalls for time saying it is difficult to organize their participation. Salim demands the army stop prowling on their roof and walls. The sounds outside disappear. Salim then demands to speak to the BBC, and Max reluctantly agrees, but urges Salim to release another hostage. Salim tells Max how his people are tortured and oppressed by the Persians. Afterwards, Salim releases another hostage. The hostage tells Gullan that the terrorists are making plans to kill all the hostages if their demands are not met.Meanwhile the press portrays hope for a peaceful ending. The political leadership approve the immediate implementation of the SAS deliberate action plan as soon as there is proof of murder.On Day 5, the SAS practices their assault on the embassy on a mock-up of the floorplan constructed in a barracks. The caretaker (Ajay Vasisht) of the embassy building is invited to the site and points out their errors in the floorplan reproduction. The Prime Minister and the Arab League remain at loggerheads limiting the League's participation. The Iraqis offer to help but British intelligence learns Sami Mohammed Ali, an Iraqi operative, likely smuggled the weapons into the United Kingdom in diplomatic bags. One day prior to the attack, Ali fled the country.Salim calls Vernon again. Vernon assures Salim that his demands will be read out in full on the BBC at 6:00 p.m. that evening. Salim says failure to follow through will lead to one hostage being killed every half hour. Inside, Trevor Lock tells the BBC reporter Sim Harris (Sam Snedden) who also being held that he feels like an animal being readied for slaughter and is considering his options in using his weapon.As 6:00 p.m. approaches, the SAS team moves into place. The local BBC News only delivers a headline regarding the terrorists' demand for an airplane to leave the country. The phone rings and Max hesitantly answers it. To his surprise, Salim thanks him for his efforts and offers to release two hostages. Only then does Max learn that the BBC World Service has broadcast the terrorists' statement in full, giving the reason for their actions as the oppression by the Iranian government in Arabistan.Katie Abie reports that two hostages were released. The SAS team stands down. Back in their quarters, Firmin suggests that the SAS team missed their chance to free the hostages but implies the challenge still lies ahead of them.On Day 6, Faisal Jaseem berates an Iranian hostage of his leader's responsibility for murdering. his people. Faisal threatens to make an example of him. Katie Adie reports that Radio Teheran is reporting that an assault is imminent though British spokesmen say negotiations are ongoing. PC Trevor Lock is separated from the other hostages. Firmin spends his time studying the faces of the terrorists and the hostages learning who should not be shot. He compares his own background to that of Faisal stating he believes if Faisal is backed into a corner, he will fight his way out with nothing to lose. Lock places a call to Vernon and tells him that a hostage is tied up downstairs and believes the terrorists will kill him if their demands are not met.Salim grabs the phone and demands a bus and the ambassadors to take them to the airport immediately. Faisal has tired of all the talking and blames the Iranian leader Khomeini for killing his countrymen. The hostage says that he welcomes his own death if it leads to Faisal's death. Despite Salim's pleas, Faisal shoots the hostage in the head three times. The SAS team get word from Hector Gullan that shots have been fired in the embassy. Max asks Salim if a hostage was killed. Salim responds that they have 30 minutes to meet the terrorists demands or more hostages will be killed and tells Max they can collect the body. Firmin suggests that the negotiators have Salim on the telephone to give the assault team the maximum amount of time to breech the building.With that, Home Secretary Whitelaw authorizes the SAS operation and control of the operation is signed over to the regiment. The Prime Minister instructs Colonel Rose that no blockage or smokescreen should be created to block the television cameras so that the world and British people can see how the British government deals with terrorists. Vernon is instructed to do anything to stall or distract the terrorists from the assault.Vernon calls Salim to discuss buses with Salim while Roy lowers the distraction charge down the light tube. Salim knows Vernon is lying. The press sees movement of SAS team on the roof and around the building. Roy reports the distraction charge is in place. Salim tells Vernon that the bus must have curtains and that Max must drive the bus. He then hands off the phone to Lock. Lock tells max he finds it unbelievable that the government is giving in to the demands of the hostages. Max tells Lock he has his demands from the government.Meanwhile, SAS agents have lowered themselves on ropes to enter the upper story through the windows and race ladders to their placement on the ground. An agent puts his foot through a window causing Salim to become suspicious and leave the telephone. The distraction charge is exploded. The press and police race for cover.Firmin's team places explosives on the front balcony to gain entrance. Firmin has to improvise when one agent gets hung up in the ropes and a selected placement of an explosive would kill the man. The SAS enter the building. Sim Harris is among the first hostages to escape. The team begins working their way through the building clearing stairwells and rooms. Four female hostages are found and sent down the stairs. A blocked door requires Firmin to find an alternate entry into a room. He returns to the balcony and enters through an exterior window. He encounters a terrorist who shoots at him. Trevor Lock is found wrestling with Salim over his gun when agents break into the room and exterminate Salim. The SAS team comes upon a room full of hostages and kill three of the terrorists. While the hostages are being hustled outside, Firmin recognizes Faisal hiding among them and shoots him in the stomach before Faisal can detonate a grenade. Outside the Embassy, the hostages are detained and searched, revealing the sixth and last terrorist trying to hide among them, and he is arrested.During the assault, led by Firmin, Salim and four of the other terrorists are killed, at the cost of one of the hostages and none of the SAS men. Firmin's gun and the grenade he claimed from Faisal are bragged as evidence for the inquiry. A visibly shaken Vernon telephones his wife to reassure her that he is safe. The SAS team rides back to Hereford, hearing the Prime Minister's effusive praise of them and the Metropolitan Police on the radio.