The Japanese sect Aum Shinrikyō, founded by self-appointed guru Asahara Shōkō in the 1980s, differs markedly from Peoples Temple and the Branch Davidians. The two American groups killed protagonists and then died themselves. Aum Shinrikyō went much further; it perpetrated an unprecedented act of indiscriminate murder. How and why, on 20 March 1995, did this religious movement launch its deadly sarin gas attack in the Tokyo subway system, killing twelve people and injuring thousands?