The London Siege was first put into effect when British Prime Minister James Wilson was mysteriously killed. The Barkawi Arms Network would then attempt to assassinate several leaders of Western nations in retaliation of the death of his family members. Many of them also disguised themselves as the Metropolitan Police, Queen's Guard, and first responders to coordinate the attacks.
After Benjamin Asher and several other world leaders arrived in London to attend the funeral, one officer secretly attached a bomb to the limo of Canadian Prime Minister Robert Bowman. A few seconds later, the limo exploded, killing Bowman and his wife.
Several imposter disguised as the Metropolitan Police killed the regular police officers before more terrorists joined the fight. Though Mike and Bronson took out some of the terrorists, the U.S and British security details were decimated.
While Italian Prime Minister Antonio Gusto and his wife were watching the scene from Westminster Abbey in shock, a bomb detonated on one of the towers, killing them. Several more civilians were killed by the falling rubble.
Unable to seek refuge with Leighton Clarkson or use The Beast, Mike requested a Land Rover to take them back to London Stansted Airport so they could escape via Air Force One. While attempting to draw the terrorists off, Bronson was killed before he could escape with Ben, Lynne and Voight. The four were pursued through the streets of London by more terrorists. In the ensuing chase, all the terrorists chasing them were killed, though Voight was fatally shot and bled out. Once they boarded Marine One to get to the airport, they would face a threat of stinger missiles. Marine Two and Marine Three were taken out, leaving Marine One defenseless. As Marine One was about to be shot down, Mike told everyone to brace for impact, leaving the three for horrified what was about to happen. Marine One crashed in Hyde Park. Though Ben and Mike survived, Lynne was fatally injured and died of her wounds, but not before telling Mike to stay alive and to make the terrorists pay as Mike tearfully watched his boss die.
Jax found Lancaster as he was trying to flee the country and confronted him on his actions before demanding him to surrender. When Lancaster refused to turn himself in as his treason would most likely result in execution, Jax shot Lancaster dead after he tried to go for the gun in his truck.
Later, Barkawi receives a call. Though he assumed it was Kamran at first, he was shocked when it was Trumbull who called. Socked and angered, he warned the Vice President that his war wasn't over. When Trumbull advises Barkawi to look out his window, Barkawi looks up and gives a defeated smile. Seconds later, another drone strike hits the compound, putting an end to Barkawi for good and avenging the fallen world leaders and all those who perished in the London Siege.
The London Siege was impacting, especially to Western countries. The attack decimated parts of London and five G7 leaders were assassinated with only Leighton Clarkson and Benjamin Asher surviving. Several civilians, Metropolitan Police officers, and Secret Service agents were also killed, including Secret Service Director Lynne Jacobs. However, President Asher's assassination was thwarted in time, thanks to Mike Banning and a joint SAS/Delta Force team led by Davies.
However, 2 weeks after the attacks and subsequent death of Aamir Barkawi by another drone strike, parts of London were being reconstructed and Clarkson's reign as Prime Minster begun with a new government installed. Mike and Leah had also given birth to their new daughter whom Mike decided to name after his late boss in her honor. After hearing a speech from Vice President Trumbull on TV, Mike decided to delete his resignation letter and continue to serve in the Presidential Detail.