Inmaculada Castillo’s life took a tragic change for the worse in 1994, when her husband was killed in a traffic accident. She had two children, Cristina and Pablo, who were aged nine and five at the time, respectively. Life became difficult; the company where she worked as a secretary went out of business and she was left without a job. She began working at the Confederation of Widows of Madrid, where she was promoted to the position of accountant. She was planning to continue her career in the human resources area. She normally went to work later, but on the morning of 11 March she had a meeting and left home early.
11 March 2004 fell on a Thursday. Early that morning, a number of terrorists with links to Al-Qaeda planted thirteen bombs on four suburban trains covering routes running through Madrid. Ten of the bombs exploded between 7.37 and 7.39 am, when the trains were at Atocha, El Pozo and Santa Eugenia stations and alongside Calle Téllez. 191 people were killed in the attack and around 1,500 were wounded. It was the deadliest terrorist attack in Spanish history. On 3 April 2004, agents from the Special Operations Group (GEO) were about to enter an apartment in Leganés where the perpetrators of the attacks were believed to be hiding when the terrorists detonated twenty kilograms of explosives in an act of collective suicide. The ensuing blast killed one of the officers, bringing the total number of people killed by the 11 March bombers to 192.