Jo Cox grew up in Heckmondwike, a few miles from where she would later die. She was the first member of her family to go to university, studying at Cambridge, and spent the years before politics working for Oxfam, the international development charity Sightsavers, and the Bill and Melinda Gates Foundation. She had a particular passion for Syrian refugees and for the work of the White Helmets, the volunteer civil defence force who pulled survivors from collapsed buildings in Aleppo and elsewhere. Earlier in 2016 she had personally nominated the White Helmets for the Nobel Peace Prize, gathering twenty fellow MPs and twelve high-profile public figures including George Clooney and Michael Palin to support the nomination. She was elected to Parliament in May 2015 and used her maiden speech to talk about the unity she saw in her diverse Yorkshire constituency. She had spent the morning of 16 June 2016 campaigning for Britain to remain in the European Union. That afternoon she was heading to her regular constituency surgery at Birstall library.

She never made it inside the library. Her killer attacked her in the street, shooting her with a modified hunting rifle and stabbing her fifteen times. Bernard Carter-Kenny, a 77-year-old retired mines rescuer who had survived the Lofthouse Colliery disaster of 1973, was waiting for his wife outside the library when he saw what was happening. He intervened, and was stabbed for it. He was later awarded the George Medal for his bravery, and he died of cancer in August 2017, aged 79. Cox died of her injuries shortly after being admitted to Leeds General Infirmary. Another witness followed the killer, and police constables Craig Nicholls and Jonathan Wright arrested him unarmed about a mile away. They received the Queen's Gallantry Medal. The killer was tried at the Old Bailey in November 2016 and sentenced to a whole life term, meaning he will never be eligible for parole. The judge ruled the murder a terrorism offence. He has spent every day since in prison.

Brendan Cox issued a statement on the day his wife was murdered that became, almost immediately, a touchstone for how Britain would respond. Today is the beginning of a new chapter in our lives, he wrote. More difficult, more painful, less joyful, less full of love. He said he and the family would work every moment of their lives to love and nurture their children and to fight against the hate that killed Jo. Hate doesn't have a creed, race or religion, he wrote. It is poisonous. Jeremy Corbyn called it one of the most moving statements he had ever heard from someone so recently bereaved. The Queen wrote a private letter of condolence. Flags flew at half mast on the Palace of Westminster, Buckingham Palace, and 10 Downing Street. Parliament was recalled. At the memorial sitting, MPs from opposing parties briefly broke convention to sit together rather than divided by party. A fund established in her memory raised over a million pounds in four days; £375,000 of it came from fines collected after the Libor scandal.

On what would have been her 42nd birthday, 22 June 2016, friends organised an event in Trafalgar Square called More in Common. Similar gatherings happened in Batley and Spen, Auckland, Paris, Washington D.C., and Buenos Aires. A year later, the Jo Cox Foundation launched the Great Get Together, weekend events of picnics, street parties, and concerts modelled on Jo's principle that her diverse constituency had more uniting than dividing it. All four living former Prime Ministers, John Major, Tony Blair, Gordon Brown, and David Cameron, recorded a joint tribute video. U2 dedicated Ultraviolet to her on the UK leg of their 2017 Joshua Tree Tour. A street in Avallon in France was renamed Rue Jo Cox. The Italian Parliament established a cross-party committee on intolerance and hate crime named in her honour. The White Helmets remembered the MP who had championed them. Tracy Brabin was elected to the Batley and Spen seat in October 2016 after the Conservatives, Liberal Democrats, UKIP, and Greens stood aside as a mark of respect. Jo Cox's murder was the first killing of a sitting British MP since Ian Gow was killed by the Provisional IRA in 1990. The week after she died, Britain voted to leave the European Union, a referendum she had been campaigning to stop. Her widower has said he hopes her death has meaning in persuading people that we hold more in common than that which divides us. That, she would have agreed, was always the work.